How much does your builder know about FE's. It sounds like one of my rebuilds from a builder that said he knew all about FE's but after 3 rebuild it was clear he was in the dark. I would pop the dist. out and hook up a drill to turn the
oil pump and if you can see
oil flowing out the front of the block down on your drill rod he forgot to install an
oil plug by #5 cylinder.
Fred