I have a stripped down '83 which came with a 4cyl and automatic trans. It's been sitting in the shed for close to 10 years. Someone in the family was going to fix it up but he gave up quickly.

Anyway, Once again I'm thinking of fixing it up. I have a TBI on it's last leg out of a truck. Thinking of a rebuild, swapping TPI injection on, using a good manual transmission. No idea what to use, as I haven't looked into this stuff in several years. And I know I need a stronger rear end (It won't be babied, will see some drag strip time). NOS likely.

What I've wanted to do for the last 25 years is stick a Big Block in it. ...

It's interior has seen better days, so I also thought of a 4th gen Parts car. Swapping what I can into it. I don't know much about them, only that the interior can swap, as well as the rearend. I guess I'm rambling at this point. Just trying to put together some ideas. Thanks...

 

4th gen rear isn't enough stronger to be worth it, especially for a sprayed rat with a stick on slicks. But it is wider, requiring mismatched wheels.
No point putting money into doing all that to an LO5, you can get someone else's unfinished project 350 cheaper if you look around.
If you want to end up with a 454, then start with a 454. Patriot shorties are far cheaper than Hooker's long-tubes.
There are no good options for a salvage-yard manual trans for what you propose, I'd think a TKO600 would be the best match, but they aren't cheap.
For the rear, there are a few options, but the 9" Ford seems best to me for what you posted.
I'm in much the same boat as you, I keep waffling on what to do with my '86, it hasn't run in too long, even a 200 HP 350 would be better than the car just sitting neglected, I've already done an LSx swap to the car, before giving that engine to my still-just-sitting S-10, and I'd really like to put the '96-'00 7400 heads on a '91-'95 TBI 454 bottom end. I just got a bellhousing from a '91 IROC-Z with a T5, but a T5 won't survive any 454.