Welcome to the barn! I bought a non running engine, no guarantees about cracks, for $75.
No Starter, manifolds, or carb. I was warned here to check the center main. I did and it was shot. It cost me $700 for new mains, rods were ok. Well sorta. #3 wrist pin was loose and it clunked when it was cold. And... If you should get into the same problems I had,Do yourself a favor and get adjustable lifters($75) for it. You'll have the engine all torn down anyway. Check the cylinders for piston fit. Maybe you'll need the next increment up in piston size and a lap to enlarge the cylinder. Check the valves for fit and looseness (are they free?). Blocks tend to crack along the left hand side under the head. The rear under the throttle linkage, In the valve chamber. and of course into each cylinder from the top. Some are an easy fix, some are not. Check the head for cracks. You'll probably discard the old head and put a new, high compression head for more power. When you're reassembling the engine. don't be shy about asking for some tips, like how many times do I have to torque the head bolts? It's all here, just ask!
Terry