Have you looked into or ever handled the more "pistol grip" style stocks? They let you're hand rest in a more upright postion like a thumbhole but don't restrict like a thumbhole can sometimes. (what jd3006 is a great example)

http://www.rifle-stocks.com/target_style's.htm

Have several styles. Thumbhole and the type I'm speaking of. If you're gonna go the way or restocking something they've got alot of options and very good prices.