If you don't get an answer here, try asking over on the
www.doublegunshop.com "Doublegun BBS" forum. Lots of doublegun fanatics over there.
Have you tried the obvious: Gunparts/Numrichs? They have had late Savage shotgun parts in the past.
I had a 20 guage 333 that I got cheap because it had been stepped on by some....fellow, and cracked straight thru the wrist. I sent it to a guy in Alabama that called himself The Stock Doctor, and he glued it so that the break didn't even show. I shot it for a few years and then traded it off, but the stock was sound. (I believe this guy is gone now....he always signed correspondance "Your Brother in Christ," which always moved me, although I am not generally churchy. He was an honest workman and businessman, which is good enough proof for me.). Whole point of this ramble is that you might well find someone who can fix the existing stock.
I too have a 333 12 guage, a gift from my wife, and cherish it.