55.2-59 Help with my automotive ignorance pls

[Phungki]

So I might have a line in a donor vehicle which is pretty cool since I’m getting close to that stage of the build. I’ve been researching of course the ins and outs the best I can on this forum and other google searches. The vehicle is supposed to have a running 350 but who knows how good lol.
I’ve read that whatever angle the engine/tranny points down is the same angle that the rearend points up. If I’m wrong pls correct me on it. I’ve also rear that ppl shift the motor to the passenger side to allow for steering and headers. Makes sense sorta. Doesn’t that put it out of alignment with the rearend? I thought Chevy rearend were centered. Mine is out of a 76 trans am. Or is it just not important?
Also what mounting brkts, engine and transmission, should I be looking to using? A link would be helpful. My truck was a 6 cyl manual transmission. So I’m pretty sure a 350 with a auto tranny won’t bolt right up either. I’m not sure what transmission is in it yet just know it’s automatic. It’s coming out of a 70 something Monte Carlo.
Your advice is always appreciated
Except if you tell me to make my own brkts. Not going to happen