The 336 is an excellent rifle. Sounds like you made the guy really happy. The price wasn't bad either. I don't see the Marlin as a better rifle than the 94 other than it's ease of mounting a scope. I've owned both and never had a problem out of how they shot. If the guy is white tail hunting you can't go wrong with the 30 30. It's taken more deer to the table than any other two other calibers.With that Hornady Lever Evolution ammo it's a beast of a round.
I've refinished stocks a dozen different ways. I don't guess I have a favorite method. I used a stain and carnauba car wax on one (old 10-22). That stock is still one of the best looking ones I ever did
When you find a way that works for you though don't let anyone try to fix what you don't see as broke.