Looks like a Savage model 24 Should be easy to find parts for it. Stock will clean up nice, forearm shouldn't be too hard to find. The selector button comes off these a lot from what I've seen. I prefer the toggle on the hammer...it stays in place! 22lr over 20ga?
I believe he can use a Stevens 94 forearm, but it's not the cheapest part to buy unless it's a 12 gauge.