big block a body swap

There's quite a few on here.

Before suggesting headers, it would be better for you to tell us what trans you're planning to run.

Cage isn't necessary for the street, but if you're planning any track time, it's not a bad idea.

Slant 6 bars are good, but a little thicker, maybe 318 A/C bars or bigger, could improve handling.

I'd suggest checking out some members builds to get ideas.

Good luck with your build.