holley help please 750 vac.

What kinda distributor do you have? Is this a points style ignition? If it is, do I really need to keep askin questions? Also, you said the accelerator pump was replaced. Have you LOOKED down the carburetor throat and SEEN then thing pumpin fuel? check the plug wire and coil wire boots. If they've dried out and cracked over time, leakin voltage will cause mayhem to ensue. Start up the engine at night and raise the hood. See a fireworks show? There's your problem.