compliance
The 922r compliance laws are a fact and I would not want to run afoul of same. That said, a clunky thumbhole stock can ususally be swapped out along with an appropriate number of "other" parts, to get a legal, proper looking AK. HOw easily the swap happens likely varies AK to AK.
Some receivers are slant cut and welded shut to hamper the very mod you mention. The MISR-90 falls into that group. Some others of the thumbhole family are much easier.
Read (and reread) the 922r rules, get a grip on parts count and have at it.
Stock, handguards, pistol grip, trigger group/hammer are likely sufficient but read up and get it right. ( I think it's 6 US parts) There are other options too, like US mags/assm's and muzzle brakes, gas piston, etc.