360 Backfires Under Load

The pump shot looks good- really squirts in there, left side is a little more pukey than the right. I bought a new Accel supers stock chrome coil and hooked it up with the ballast res that came with the MP ignition. Vacuum was up to 15 and stready, timing looked like 15 before the mark I came up with and about 25 before on the stock tab so I left it alone- though since the vacuum reading went up a few inches and steadied maybe the coil had cured it

drivability improved somewhat but the 1-2 shift causes backfire, have not run it over 35 mph

I read somewhere it was critical for engines to start quickly or it could damage the cam- I don't think it started quickly. I used the Rotella ;) but I had the dizzy 180 out. Went through a round of cranking(probably more than I would care to admit) changed the carb, another round but less cranking and I found the distributor problem. It started and ran but the driveability problems were present. I was really spooked it would not start so I checked everything(LOL) and I tried to keep the cranking/starting attempts short, for what it is worth and I had prelubed it.

Starts pretty easy, restarted when the backfire killed it driving and the idle sounds pretty good. The manifold flanges are leaking at the down pipes so there is always a racket.

Play with the timing more? Do I pull the valve covers and look for rockers not moving? :banghead: