Marshall vs. Queen Endgame In a game of "Sort of Almost Chess", the variant from Mr. Betza that replaces one of the queens with a Marshall (the Rook+Knight compound, also known as the Chancellor, or the Empress in Fairy Chess circles), this surfaced as a possible endgame that was narrowly avoided by a slightly controversial promotion by Black. The Marshall and Queen are represented in the diagram as Knight and Bishop, respectively (given that they can both move as rooks).

    [Date "2018.06.26"]
[Round "-"]
[White "NN"]
[Black "James"]
[Result "?"]
 [FEN "7B/8/6K1/8/8/1k6/6P1/n7 w - - 0 1"]


Given that Black's to move, I'm wondering if it's possible for either side to get a win from this position. A Black Queen (the promotion that actually took place instead of this position) is a forced win for Black with careful play, and Marshall vs. Marshall is almost certainly a draw, but the similar yet different power of the pieces here makes it a complex problem.
Since my Stockfish fork for fairy chess variants already supports Almost Chess, I added Sort of Almost Chess with both sides having all promotion options (which is what you seem to imply in your question).

I ran a search on the given position up to depth 50 with the commands below:

setoption name hash value 1024
setoption name multipv value 30
setoption name UCI_Variant value sortofalmost
position fen 7Q/8/6K1/8/8/1k6/6P1/c7 b - - 0 1
go depth 50


The results below state that white is winning (latest in 23 moves) irrespective of black's next move. Going through some of the variations in the output it seems relatively clear that the chancellor has no way to give a perpetual, so white is able to advance the pawn and finally either promote or force the exchange of queen and chancellor.

info depth 50 seldepth 47 multipv 1 score mate -23 nodes 860106805 nps 1814762 hashfull 355 tbhits 0 time 473950 pv a1a4 h8f6 b3a2 f6e6 a2b2 e6e2 b2c1 e2e3 c1c2 g6f7 a4a5 e3e2 c2b3 e2d3 b3a4 d3d4 a4b3 d4b6 b3a4 b6a5 a4a5 g2g4 a5a6 f7f6 a6b7 g4g5 b7a7 g5g6 a7a6 f6e5 a6b5 g6g7 b5c4 g7g8q c4c3 e5e4 c3c2 e4d4 c2b2 d4c4 b2c2 g8g2 c2d1 c4d3 d1e1 g2g1
info depth 50 seldepth 47 multipv 2 score mate -23 nodes 860106805 nps 1814762 hashfull 355 tbhits 0 time 473950 pv a1e1 h8b8 b3a2 b8a7 a2b3 a7b6 b3c4 b6a6 c4b4 a6d6 b4c4 g2g4 e1a1 d6c6 c4b4 c6e4 b4b3 e4d3 b3b2 d3d4 b2a2 d4a1 a2a1 g6f5 a1b2 f5e5 b2b1 g4g5 b1c1 g5g6 c1d1 g6g7 d1e2 g7g8q e2f3 g8b3 f3e2 e5e4 e2f2 e4f4 f2g2 b3c2 g2f1 f4f3 f1e1 c2c1
info depth 50 seldepth 45 multipv 3 score mate -22 nodes 860106805 nps 1814762 hashfull 355 tbhits 0 time 473950 pv a1g1 h8b8 b3c2 b8c7 c2d3 c7d6 d3e4 d6b4 e4d3 g2g4 g1h1 b4d6 d3e3 d6e5 e3f2 e5f4 f2g1 f4c1 g1h2 c1h1 h2h1 g6f5 h1g2 g4g5 g2f2 g5g6 f2f3 g6g7 f3e3 f5e5 e3d3 g7g8q d3e3 g8b3 e3e2 e5e4 e2f2 e4f4 f2g2 b3c2 g2f1 f4f3 f1e1 c2c1
info depth 50 seldepth 45 multipv 4 score mate -22 nodes 860106805 nps 1814762 hashfull 355 tbhits 0 time 473950 pv a1f1 h8f6 f1g3 g6f7 g3h1 g2g4 h1h7 f7g6 h7h3 g4g5 b3a3 g6f7 a3b4 g5g6 h3h6 f7e6 h6g4 g6g7 b4c4 e6f7 g4g1 f6c6 c4d3 c6g6 g1g6 f7g6 d3e4 g6f6 e4f4 g7g8q f4e4 g8c4 e4f3 c4d3 f3g2 d3e2 g2h3 e2f2 h3g4 f2e3 g4h4 f6f5 h4h5 e3h3
info depth 50 seldepth 45 multipv 5 score mate -22 nodes 860106805 nps 1814762 hashfull 355 tbhits 0 time 473950 pv a1d1 h8f6 b3a4 f6c6 a4b4 c6b6 b4c4 g2g4 d1e1 b6d6 e1a1 d6c6 c4b4 c6e4 b4b3 e4d3 b3b2 d3d4 b2b1 d4a1 b1a1 g6f5 a1b2 f5e5 b2b1 g4g5 b1c1 g5g6 c1d1 g6g7 d1e2 g7g8q e2f3 g8b3 f3e2 e5e4 e2f2 e4f4 f2g2 b3c2 g2g1 f4f3 g1h1 c2g2
info depth 50 seldepth 43 multipv 6 score mate -21 nodes 860106805 nps 1814762 hashfull 355 tbhits 0 time 473950 pv a1c1 h8f6 b3a3 f6d6 a3b3 d6d7 c1c5 d7d1 b3a2 d1d2 a2b3 d2e3 b3b4 e3c5 b4c5 g2g4 c5d6 g6f7 d6c6 g4g5 c6d7 g5g6 d7d6 f7f6 d6d5 g6g7 d5e4 g7g8q e4e3 f6e5 e3f3 g8b3 f3e2 e5e4 e2f2 e4f4 f2g2 b3c2 g2g1 f4f3 g1h1 c2g2
info depth 50 seldepth 43 multipv 7 score mate -20 nodes 860106805 nps 1814762 hashfull 355 tbhits 0 time 473950 pv a1a6 h8f6 a6a4 g6f5 b3a2 f6e6 a2a1 e6e1 a1a2 e1d2 a2a3 d2d3 a3b4 d3e4 b4b5 e4a4 b5a4 g2g4 a4a3 f5e5 a3b2 g4g5 b2b1 g5g6 b1c1 g6g7 c1d2 e5e4 d2c2 e4d4 c2b3 g7g8q b3b2 d4c4 b2c2 g8g2 c2d1 c4d3 d1e1 g2g1
info depth 50 seldepth 41 multipv 8 score mate -20 nodes 860106805 nps 1814762 hashfull 355 tbhits 0 time 473950 pv a1c2 h8b8 b3a2 b8a8 a2b3 a8d5 b3b2 d5e4 c2c1 e4b4 b2c2 b4c5 c2b1 c5c1 b1c1 g2g4 c1d2 g6f5 d2d1 g4g5 d1e2 g5g6 e2e3 g6g7 e3e2 f5e5 e2e3 g7g8q e3f3 g8b3 f3e2 e5e4 e2f2 e4f4 f2g2 b3c2 g2g1 f4f3 g1h1 c2g2
info depth 50 seldepth 39 multipv 9 score mate -19 nodes 860106805 nps 1814762 hashfull 355 tbhits 0 time 473950 pv a1a5 h8b8 b3a2 b8d6 a5a4 d6d5 a2a3 d5d3 a3b2 d3b5 b2a3 b5a4 a3a4 g6f6 a4b5 g2g4 b5b6 g4g5 b6a7 g5g6 a7a6 f6e5 a6b5 g6g7 b5c4 g7g8q c4c3 e5e4 c3c2 e4d4 c2b2 d4c4 b2c2 g8g2 c2d1 c4d3 d1e1 g2g1
info depth 50 seldepth 31 multipv 10 score mate -15 nodes 860106805 nps 1814762 hashfull 355 tbhits 0 time 473950 pv a1a3 h8h3 b3b4 h3a3 b4a3 g2g4 a3b4 g4g5 b4c5 g6f6 c5c6 g5g6 c6d6 g6g7 d6c5 f6e5 c5c4 g7g8q c4c3 e5e4 c3c2 e4d4 c2b2 d4c4 b2c2 g8g2 c2d1 c4d3 d1e1 g2g1
info depth 50 seldepth 31 multipv 11 score mate -15 nodes 860106805 nps 1814762 hashfull 355 tbhits 0 time 473950 pv a1a2 h8g8 b3b2 g8a2 b2a2 g2g4 a2b3 g4g5 b3b4 g6f5 b4b5 f5e5 b5b6 g5g6 b6c5 g6g7 c5c4 g7g8q c4c3 e5e4 c3c2 e4d4 c2b2 d4c4 b2c2 g8g2 c2d1 c4d3 d1e1 g2g1
info depth 50 seldepth 31 multipv 12 score mate -15 nodes 860106805 nps 1814762 hashfull 355 tbhits 0 time 473950 pv a1b1 h8b8 b3c2 b8b1 c2b1 g2g4 b1c2 g4g5 c2d3 g6f5 d3e2 g5g6 e2e3 g6g7 e3e2 f5e5 e2e3 g7g8q e3f3 g8b3 f3e2 e5e4 e2f2 e4f4 f2g2 b3c2 g2g1 f4f3 g1h1 c2g2
info depth 50 seldepth 29 multipv 13 score mate -14 nodes 860106805 nps 1814762 hashfull 355 tbhits 0 time 473950 pv b3a2 h8a1 a2a1 g2g4 a1b2 g4g5 b2a1 g6f6 a1b1 g5g6 b1a2 g6g7 a2b2 g7g8q b2c2 g8g3 c2b2 f6e5 b2a2 e5d4 a2b2 g3c3 b2a2 c3b4 a2a1 d4c3 a1a2 b4b2
info depth 50 seldepth 21 multipv 14 score mate -10 nodes 860106805 nps 1814762 hashfull 355 tbhits 0 time 473950 pv a1a7 h8b8 a7b7 b8b7 b3c4 g6f5 c4c5 f5e5 c5c4 b7f3 c4b5 f3c3 b5a6 e5d6 a6a7 c3b2 a7a8 d6c6 a8a7 b2b7
info depth 50 seldepth 19 multipv 15 score mate -9 nodes 860106805 nps 1814762 hashfull 355 tbhits 0 time 473950 pv a1h1 h8h1 b3c3 h1h4 c3b3 h4d4 b3c2 g6f5 c2b3 f5e4 b3a3 e4d3 a3b3 d4b6 b3a2 d3c2 a2a1 b6b1
info depth 50 seldepth 19 multipv 16 score mate -9 nodes 860106805 nps 1814762 hashfull 355 tbhits 0 time 473950 pv a1a8 h8a8 b3b4 a8c6 b4b3 c6b5 b3c2 g6f5 c2d2 f5e4 d2c3 e4e3 c3c2 b5b4 c2c1 e3d3 c1d1 b4b1
info depth 50 seldepth 17 multipv 17 score mate -8 nodes 860106805 nps 1814762 hashfull 355 tbhits 0 time 473950 pv b3b4 h8a1 b4c4 g6f5 c4d3 a1a4 d3e2 a4d4 e2f1 f5g4 f1e2 g4g3 e2e1 g3f3 e1f1 d4a1
info depth 50 seldepth 17 multipv 18 score mate -8 nodes 860106805 nps 1814762 hashfull 355 tbhits 0 time 473950 pv b3a3 h8a1 a3b3 a1d4 b3c2 g6f5 c2b3 f5e4 b3a3 e4d3 a3b3 d4b6 b3a2 d3c2 a2a1 b6b1
info depth 50 seldepth 17 multipv 19 score mate -8 nodes 860106805 nps 1814762 hashfull 355 tbhits 0 time 473950 pv b3c2 h8a1 c2d3 g6f5 d3c4 a1a4 c4d3 f5f4 d3c3 f4e3 c3b2 e3d3 b2b1 d3c3 b1c1 a4a1
info depth 50 seldepth 17 multipv 20 score mate -8 nodes 860106805 nps 1814762 hashfull 355 tbhits 0 time 473950 pv b3a4 h8a1 a4b3 a1d4 b3c2 g6f5 c2b3 f5e4 b3a3 e4d3 a3b3 d4b6 b3a2 d3c2 a2a1 b6b1
info depth 50 seldepth 17 multipv 21 score mate -8 nodes 860106805 nps 1814762 hashfull 355 tbhits 0 time 473950 pv b3c4 h8a1 c4b3 a1d4 b3c2 g6f5 c2b3 f5e4 b3a3 e4d3 a3b3 d4b6 b3a2 d3c2 a2a1 b6b1