Misfiring issue

Thanks for the help guys, I'll try and answer all your questions. The missing is a very audible backfiring out the exhaust, with a pronounced shudder through the car with each one. You have more time to notice it in high gear, and it's on it's face and popping not much after 5,000, and really struggling to get through the traps. The wires are just new Accels, I have not ohm tested them.

I did check the relucter air gap, and it was off a bit out of the box, but I corrected it. The charging system seems to be OK, (new alternator/regulator/ballast). The alternator puts out about 16.5+ volts, and it runs right around 14.5+ at the battery. I was so nervous at the track, I completely forgot to pull a plug when I got off the top end of the track. By the time I drove it all the way back to the pits, I didn't figure it would show me anything.

When I say the main body "bumped up" the carb, I mean the addition of the Proform main body makes a 750 DP into a 780 cfm. carb. I do not have jet extensions, but it will before the next trip out.

My fuel system is: Cell, 1/2" hard line to a 1/2" BG filter, Paxton 160 GPH pump, 1/2" hard line to a Holley 1/2" big port regulator, 3/8" hard line to the carb, each bowl gets it's own line.

I am not running the vacuum advance, and it has a very fast curve. It seems to be "all in" my not much more than 2,000 rpms., and it does not over advance. I think I heard that Mallory makes the new MP distributors. This one sure doesn't look like a stock MP electronic distributor inside. Thanks for all the help.