Losing my mind trying to get this 360 to run right

Ok guys so here's where I'm at. I eliminated one issue that I was having with carburation. I rebuilt my carter competition 750 and got it to idle. I'm still having a backfiring issue so I threw the timing light and vac gauge on there and the timing mark was waaaaay advanced and would hardly move back when when I tried retarding it. I thought I nailed my cam timing when I put it in at mfg specs but is it possible that could be that far off? For the most part when I installed it, it degreed out at pretty much straight up within a degree or so. I'm not worrying about it being to the nats ***. My dizzy I bought from KMJ performance on ebay. I haven't been real happy with it it's mainly a stock style distributor but aluminium and has a built in hei style system. Does that sound like it could be the culprit? Firing order is right on compression checks out great but I think I'm going to have to pull the chain cover and make sure my cam is where it needs to be. Could it have skipped a tooth? Its a new double roller so I'm just scratching my head. Any other input is appreciated.