Alright guys, I didn’t get any help from the fb group I went to..so here I am! Sorry in advance because my plans are a mess for this truck right now. So I just recently picked up a 91 c1500 w/t with the 4.3 and 700r4. The trans feels strong and doesn’t give me any major red flags, but the engine... smokes like a train (currently trying to narrow down between valve seals, drain channels in the head, egr or pcv), heat riser in the intake doesn’t work, runs really rough, BUT only has 145k on the clock and doesn’t leak any fluids I’ve got a doner truck with the cfi vortec 4.3 and an iffy 4l60e. Would it be worth it on the current motor to fix the oil consumption and swap the vortec heads and cam from the doner for a reliable power bump or does it sound like that motors not worth the effort? Any modifications besides just swapping the parts over? If I swap the cfi and harness into the 91 would it be able to work with the 700r4 since it doesn’t have an electronic transmission to control and I don’t trust the 4l60e in the doner? If so what all parts would need to be swapped or replaced/upgraded besides engine, ecu, and harness? Or is it better for me to just buy a tbi 305 and slap it in? I know it’s all over the place but I’d like your input on which route would be the best balance of simplicity, reliability, and performance. I’m not a newbie to mechanical work but this would be my first motor swap and I work ALOT so I didn’t want to get stuck in the middle of something I wasn’t prepared for and end up with my truck down for weeks. Thanks!