Not mentioned in this discussion that I can see is that most throughbolt stocked guns can be adjusted for cast by reinleting the head of the stock.
I had this done to a K80 by the Krieghoff shop about 30 years ago. They increased cast off @ the heel by 1/4" & fit to the head of the stock & tang remained perfect. You could see that they used some epoxy bedding internally w/the stock removed.
I shot that gun for a long time & never had any issues with the work & it wasn't expensive to have done. I'm sure there are other gunsmiths out there that can do this for you. Michael Yardley mentions this method of adjusting cast in his book "Gunfitting".
