NEED HELP! Backfiring!

Hey guys, just finishing up the restoration on one of our 1969 swingers and we are having engine issues. We had the original engine rebuilt by a reputable engine shop locally. Engine was broken in and ran fantastic on the dyno. Now that we have it home and in the car, its running very strange. It is backfiring through the carb, and making small back fires (popping sound) out of the exhaust as well. the 600 edelbrock that was on it was used, so i figured maybe the accelerator pump was gone and maybe it was backfiring due to being too lean and needing more carb. As a temperary solution, i put my edelbrock 850 thunder avs on it (i knew it was too much carb, but tried to see if it was a lean situation). It was running really rich, but STILL backfiring. So, i checked timing. Everything seemed spot on and we made sure it was dialed in (pertronix flamethrower distributor), still backfiring. I put brand new matching pertronix plug wires (replaced the new taylor made wires) and still backfiring. Put a new matching pertronix coil on it, still back firing. We ended up buying a brand new edelbrock 750 carb to get the fuel a little closer, and guess what, still back firing. Ive thought about a wiped cam lobe, but it was broken in properly and ran great on the dyno. Could it be a wiring issue in the car itself, an engine issue, anything? I am at a loss and have no other ideas. Has anyone had an issue like this? Thank you for your help in advanced!