I purchased a 1985 743 with the engine completely torn down. I was told it overheated and cracked the head. It came with a new head. I purchased a complete rebuild kit and dropped off the block at a machine shop. They cleaned the block and installed new liners and front main bearing. Cylinder 3 had a weird ridge in the bore almost like they stopped boring half way through the cylinder. They also mag fluxed the head and said nothing was wrong with it. I installed the new head anyways. I think their overheating issue was the 20 pounds of dirt that I cleaned out of the radiator. It was so bad you could not see any light from the fins. I got the engine put back together and I just need to time the injector pump. It came with out any shims. My main question, that i cant find anywhere, is that i have two fuel lines coming from the tank. I take it one is supply and one return. The supply line is pretty simple. Tank to filter then pump, but i cant figure out where the return hooks up to. Any help will be greatly appreciated. I'm shooting for the first start this weekend. Hopefully i don't have to spend another small fortune on the hydraulic side.