Paul let me answer a couple of your questions. Since you will be pouring new bearings you can use a crank from another engine. You can also use rods from another engine. I would first try and figure out what caused the old engine to throw a rod. I would magnaflux any part that is going back into the engine. I normally just pull the engine. I would keep the caps in the correct position just so you get in the habit of doing. If you do not bore all four cyc. there is no reason to replace the pistons. Same goes for valves, springs, and guides which may be ok. Just put them in the same location that they came out of. I would change out the rings either way. You may or may not want to pull the came based on the condition of the lifters