Keith, I have never fitted a new stock. I have made a FW double trigger into a single selective trigger stock, had to mortise out the area and that leaves even less wood. The only thing I can tell you is to take your time and get the in-letting around the side-locks tight and where the metal fits against the receiver. If the wood that mates up to the receiver isn't tight, there is a good chance that it will crack around the side plates from recoil.
Good luck and keep us posted and take plenty of pictures.
I've enclosed a picture of the long trigger guard if you don't have one to see what it looks like at the end.