After scraping, I decided to soak the front half of the stock in acetone to pull out as much oil as I could from the end grain before proceeding.
I made my replacement block and glassed it on, let it set up overnight then worked it down to rough shape. Lastly, I re-inletting the frame.

Lot's to do yet. Need to get the gap at the frame edges just right, level the top of the new piece to match the other side - the tang stands proud towards the rear, so we'll match that. I'll glass bed the recoil area inside so the blowout never occurs again. I'll fill in the tiny missing pieces underneath when I do this. Most all the dents should steam up, and the scratches aren't too deep to sand out. There are a couple knicks around the buttplate edge to deal with. I can fill those in with dyed acraglass. I'm planning on a darker staining with reddish undertone to hide the repair as much as possible. The filled in areas will then disappear at the 10ft stare test.