Refute perceived differences in the Gospel between Peter and Paul from Sola Scriptura perspective What is the biblical evidence in keeping with the Protestant, Sola Scriptura perspective, for refuting a claim that Paul's gospel differed from Peter's gospel?
I see in Scripture:
2 Peter 1:1-2

Simeon Peter, a servant and apostle of Jesus Christ,
To those who have obtained a faith of equal standing with ours by the righteousness of our God and Savior Jesus Christ:
May grace and peace be multiplied to you in the knowledge of God and of Jesus our Lord.

and 2 Peter 3:13-15

But according to his promise we are waiting for new heavens and a new earth in which righteousness dwells.
Final Words
Therefore, beloved, since you are waiting for these, be diligent to be found by him without spot or blemish, and at peace.  And count the patience of our Lord as salvation, just as our beloved brother Paul also wrote to you according to the wisdom given him,

And then from the Apostle Paul:
1 Corinthians 15:3-8, 17-22

For I delivered to you as of first importance what I also received: that Christ died for our sins in accordance with the Scriptures, that he was buried, that he was raised on the third day in accordance with the Scriptures, and that he appeared to Cephas, then to the twelve. Then he appeared to more than five hundred brothers at one time, most of whom are still alive, though some have fallen asleep. Then he appeared to James, then to all the apostles. Last of all, as to one untimely born, he appeared also to me.
And if Christ has not been raised, your faith is futile and you are still in your sins. Then those also who have fallen asleep in Christ have perished. If in Christ we have hope in this life only, we are of all people most to be pitied.
But in fact Christ has been raised from the dead, the firstfruits of those who have fallen asleep. For as by a man came death, by a man has come also the resurrection of the dead. For as in Adam all die, so also in Christ shall all be made alive.

It is easy to find Scriptures where Paul clearly affirms that justification is through faith in the death, burial and resurrection of Jesus for the forgiveness of sins, and made accessible by grace.  What are the Scriptures, other than the one from 2 Peter above, which clearly indicate that this is the same Gospel of Jesus Christ which Peter received and passed along?
Peter's view that salvation is through faith in Jesus is evident. The difference is his epistles focuses more on the topic of sanctification through the Holy Spirit (1 Peter 1:2), which is a result of faith, but the underlying doctrine is the same.

1 Peter 1:5 Who are kept by the power of God through faith unto salvation ready to be revealed in the last time.
1 Peter 1:9  Receiving the end of your faith, even the salvation of your souls.
1 Peter 2:24 Who his own self bare our sins in his own body on the tree, that we, being dead to sins, should live unto righteousness: by whose stripes ye were healed.

In this next section, Bible verses also show that sanctification is a fruit of faith and is a theme preached by both apostles as a part of the gospel.
When the grace of God is received through faith, it has a sanctifying influence as we partake in divine nature (1 Peter 1:4, Romans 8:4) and die to self (1 Peter 2:5, Romans 6:6).

Romans 6:22 But now being made free from sin, and become servants to God, ye have your fruit unto holiness, and the end everlasting life.
Romans 6:12-13 Let not sin therefore reign in your mortal body, that ye should obey it in the lusts thereof. Neither yield ye your members as instruments of unrighteousness unto sin: but yield yourselves unto God, as those that are alive from the dead, and your members as instruments of righteousness unto God.

Too much emphasis is sometimes put on separating justification and sanctification. But if the heart in unrenewed, the belief of Christ is merely a theory, the seed of the gospel never takes root, and their belief is only external just as Satan and the demons also believe in Jesus.