What Greek manuscripts were used for the KJV NT other than the Novum Instrumentum omne? Erasmus famously only had 7 manuscripts on hand when he compiled the first edition of his "Novum Instrumentum omne".  However presumably as his text underwent several revisions after that, and then became the basis of the versions produced by Stephanus, Beza and the Elzavirs, and ultimately the KJV almost a century later, more scholarship was done and more manuscripts were brought in.

Or were they?  Is it possible to know how many (and even which) manuscripts were used by the Textus Receptus editors throughout the decades and ultimately served as the basis for the New Testament in the KJV?  Or does the KJV NT still primarily just rely on the the 7 manuscripts that Erasmus started with?
The King James Version is a variety of the Textus Receptus. The translators who produced the King James Version relied mainly on the later editions of Beza's Greek New Testament, especially his 4th edition (1588-9). But they also  frequently consulted the editions of Erasmus and Stephanus and the Complutensian Polyglot. 

According to Scrivener (1884), out of the 252 passages in which these sources differ sufficiently to affect the English rendering, the King James Version agrees with Beza against Stephanus 113 times, with Stephanus against Beza 59 times, and 80 times with Erasmus, or the Complutensian, or the Latin Vulgate against Beza and Stephanus.

However, at the time, in 1611, the focus of the AV translators was to produce an English bible, not a Greek text. They consulted the above texts, intelligently, and - in effect - were producing a new Greek text, an improvement on what had gone before, but they were recording their improvement in English, not in Greek.

So, in 1881, Frederick Scrivener, under contract to the Cambridge University Press, published the Greek text underlying the King James Bible. This edition of the Received Text has been republished many times, most recently by the Trinitarian Bible Society and by the Dean Burgon Society. It conforms to the KJV. 

[Compiled from online information in the public domain.]