For one thing I think you have too much timing in it. I was told once (after torching a head between 3 and 5) that if you went over 36 degrees you were risking engine damage. Also it sounds like you may have rolled the sprag in your converter, ( but you have tried 3 different converters) so that probably isn't the problem. If it looks like the advance is coming in right in your distributor, then I would not think that it would be a distrib. problem. The timing issue, 38 degrees would make it run faster on the bottom, and lay down on top. I think I would look into the 7AL box if I were you. also if the cam is not in right that could cause your problem. Sounds like maybe too much advance in the cam. Those are the two (box and cam) that I would look into. Just my two pennies.