Do you need the entire thickness of the extension block in making the new dimentions.
If the thickness of the block is oversize, you can cut the butt stock back a bit more reducing the drop line. The block moves foreward then and perhaps can make up the difference both in thickness and also catch the straight toe line all the way through.
Your grain match might suffer doing this though..
Short of that,,a new piece of wood,
I don't think you want to be installing leather covered pads to make up the difference at the other end.
