this post is answering a question I received via PM. I couldn’t figure out how to post pictures in the PM so I’ll post them here. Hope you don’t mind.
the rearend is out of a late 80’s firebird. It happened to be very close in width to original rearend. I used stock rear springs for a long time. Only within the last few years switched to posie rear springs. I made my own spring perches, and mounting plates. I incorporated the original lower shock mount. It has a lot of miles like this. I haven’t had any issues.