It's your call on the sear, just remember when parts go in the parts bins...... they do get buried over with more incoming parts.
Swap it if you want, but I'd hang on to the one coming off and tag it.

BTW, Your Recoil plate looks to fit well enough. I try to keep the under side edge clean of grime.

Cheers and nice NPM... Happy New Year..

Charlie-Painter777