Paint in engine bay etc

There are enough creases and bends in that metal that it is easy to blast without damage. I have done it a couple of times with used glass beads but they get everywhere and are hard to clean up. I have also done it with a die grinder and 3M surface conditioning discs (like Scotch Brite). That will strip it easily and in the crevices but you will have to spend a few bucks to get enough discs.
Sometimes I just hand sand the jambs.
After it is stripped, prime and paint it. I use single stage paint under the hood because clear coat is too hard and sometimes a piece will crack and break off when bolting something down.
I have done it with wiring in the car, by pulling it back and covering it.
Without some type of prep, I would not expect to get a lasting paint job.

Body shop supply stores have paint that is made for under hood and trunk areas and door jambs.They may have a tech sheet for the paint with directions.

Forum member Bruce Carothers (AMXTSY) repainted his engine bay with the engine in the car and it looks gorgeous. He won the Teague award with that car last year, so that tells you how nice it looks. That's inspired me to do the same with mine, though I can certainly understand those who would rather just pull the engine and be done with it.

I have a built engine in my old car, after I get the new car painted and interior done I'm going to tackle the swap. that way I can drive it while I get the old engine ready.