Check out the KickKiller leather pads. I use them, exclusively, for temporary stock lengthening, but they only add 1/2"+. I have increased that amount by adding "shims" inside before putting it on the gun. KKs come in four sizes. The largest should be perfect for your gun. They say it is 5.3" X 1.74", inside measurements.

I've been using them for over twenty years and have never even come close to wearing one out. Excellent product.

SRH

May God bless America and those who defend her.