Good news is that 21's are stout and can survive several redo's without worrying about wall thickness. The ribs are and lug do tend to give a bit of problem with big honking beaver tail fore ends. Not so much with splinters. I have had three, a 12, 16 and 20 with zero problems with them.
I understand your delemia about repair, upgrade or total upgrade. It's your gun fix it up as you want but always for the long term. Use it for ten years and no amount of money put into it is a big deal. Upgrade it and sell it in a year or two and you will take a big hit in the wallet most likely. So make it what you want it to be and enjoy it for the long term.
