Soooo what do I have
Not sure you're actually asking a question or not, but if you are, here is my analysis based on the photos in this thread and the other one:
You have a base-model CJ-8 that was likely someone's pseudo-restoration project at some point. The frame looks reasonably clean, which really is what counts as much or more than anything else, but there's been at least one major frame repair at the front left spring hanger, so it'd be worth taking a close look elsewhere for further cracks and rust damage. I'd probably start at the rear and work my way forward tapping it with a hammer and listening for thin spots, as well as looking for cracks and places where the C-channels may be trying to split. That being said, the bent spring at that location (front left) suggests that the frame repair (which looks amateurish) could be from an accident. I'd at least stick a bottle-jack at that bent spot in the spring and bend it straight (and I'd keep running the spring; I've done this a couple times on different Jeeps with great long-term results). It's had at least one obvious patch-panel installed for the passenger floor, which means there are probably other patch-panels. The tailgate is aftermarket. The body mounts look like they've been off not too long ago, which is also a good sign. It has the smaller (steel) fuel tank. It has obviously been repainted, and bedlined. Someone added a tach, which from the photo I can't tell if it's an OEM tach or an aftermarket tach, but either way it was not original to the Jeep since if you got the OEM tach, you also got the OEM clock. But considering that it's a 304, the OEM 6-cylinder tach wouldn't have displayed the correct RPM anyway. So, on to that 304. You should check the casting in the block, but given the t-case shifter and the fact that it's a 3-speed, I agree with your earlier assessment that it's a T-150, and the t-case is probably a Dana 20, so the whole drivetrain probably came from a '76-'79 CJ-5 or CJ-7. (It's also possible that you have a T-15 (or even a T-14), which would have been between a 304 and a Dana 20 in the early '70s.) The engine was repainted some other shade of blue, probably when it was stuffed into this frame; or even earlier (the upper portion of the bottom of the oil pan is the original AMC blue). It does not appear that you have the electronic ignition since I don't see the harness for it from the distributor, which suggests that you have a slightly earlier engine; I think the Motorcraft ignition became standard in '77, so you might check the left fender for the ignition box and/or pop the distributor cap to see if you have points. I also see the earlier style air-cleaner rather than the one that is squared at the end for connection to the grill for fresh air that would have come from a '76+ CJ. The seats and wheels are aftermarket. The stainless mirrors, grill, hood accessories, and grab-bar are aftermarket. A PO welded up custom front and rear bumpers using big angle-iron. The front shackles are a nice aftermarket replacement. The exhaust is obviously custom. The dash-pad is for non-vent doors or soft-doors. You're missing the driver's side grill support, but it looks like the bracket is missing from the firewall (I'd actually weld the bracket back to the firewall and get a replacement).
My overall assessment: this is a great little project Jeep for you! It's had a cosmetic restoration not too long ago, so as long as the rust-monster was reasonably put at bay, this will be perfect for your plans. It's not so "original" that you should feel bad modifying it at all. In fact, this is probably the PERFECT Scrambler if you DID want to modify it. But the mods that were done are pretty authentic and still "true" to AMC with the AMC V8 with the Jeep drivetrain and some basic body-work. The 2.5" lift and 33"s will make this extremely competent in the woods, and with the 304 you'll have plenty of power to turn them even if you don't change gears. So long as that crack wasn't from some accident that totally screwed up the frame, this is a great little runner that you can have fun with, that still has room for upgrades as you see fit.