Use to be while @ gun shows many M1 carbines contain a large amount of M2 parts. Round bolts, M2 trigger housings, M2 slides. These are the parts you would need on a carbine to go along with the registered parts kit. M1 to M2 parts are pretty easily installed.
I've seen a M2 bolt desinegrate, while in full auto. A new disconector lever might need tuning. The rivet on the disconnector lever can also give way. I have seen the selector levers knurled knob lost from a bad rivet. A M2 operating slide spring is a must as the M1 won't work.
I have a buddy who owns M2 carbines. They are ammo finicky! Cheap low power ammo generall won't work. He has just about every tool & part one might need for a M2 & brings them with him.