Almost no oil pressure help

Well, pull the pan and see what's going on. Black oil globs doesn't sound like something i'd expect out of a rebuilt engine. Surely whoever rebuilt it didn't put the sludged up pump back in it. I believe you will find your answer when you pull the pan off. I know it's a pain but so is rebuilding an engine too. I bet you find the problem quickly. Heck it could just be a loose oil pump or pickup.