Dropping the tank is the right thing to do gas can go bad very quickly these days best to clean the system and start fresh. It can also pick up a lot of water.
Did it run any better. Whats the timing set at. Did you retune the distibuter and vacum advance/mechanical advance systems for high compression big cam? You should be able to run flat tops with Edel heads.
Have you tried pulling some timing out of it and a lot less advance and moving your vacum soure to a different port.
Last edited by hcompton; 11-12-2012 at 08:15 PM.