Given your last sentence I'd recommend that you look at a fully assembled crate engine, using one of your problem engines as the core. Then you can disassemble the other one to better understand the way it all fits together, and still sell it for scrap by weight once your done, provided you don't decide to rebuild it for some future project. You can get a bone stock SBC with a good warranty and be on the road quickly, or you can spend more $$$ and spring for one that's built for performance. It's still the same way it was back in the day, the sign posted in the shop "Speed is $Money$, How Fast Do You Want To Go??"