Mike----you have something basic going on and are dancing around the problem-----------You just worked on the engine rebuilding the top end--------you have a poor valve job, incorrectly set lifters, vacume leak somewhere(intake ports, vaccume hoses, carb base gasket, crossed plug wires------
A new distributor is the last thing you need------
Put new wires, cap,rotor and insure that they are proper order---It is very common for a couple wires getting put on in the wrong place at the cap--if you have 7/2 mixed up 7 will fire 2 90* early-------
And another question----why did you do the rebuild????????????what was the previous symphomes??????????