Engine Timing

[Locutus]

This is my engine combo
block: 14010207 ...350...80-85...2 or 4
heads: 3782461....64-66...327......Camel hump,no accessory holes,194/150 Valves,160/62cc port volumes,62cc chamber.
Carb: Brand New Edlebrock 1406 600 CFM
Cam: Crane Energizer Part # 100072 Grind # 284 H12 ( I don't know what info you might need about the cam) It is slightly agressive and is supposed to have a fair idle.
Exhaust: Headers Dual Exhaust 2.5 inch pipe


I have a stock HEI distributor, and my problem is I can't seem to get it timed right. The only place it will seem to idle is well past the degree marks on the timing chain cover. It would be like 20-30 degrees advanced. If I try to put it down to like 4-8 degrees it dies. I recently put on a new edlebrock because the Holley 750 double pumper was way to much carb. Before I replaced the carb it would frequently back fire thru the carb, no matter where I had the timing at. I can't seem find a happy medium. This is one of the few things holding me back from driving my truck on a daily basis. Now here are the only things I can think of, The firing order is off, the cam is indexed way to much or the distributor is off a few teeth. I did not install the cam or the distributor. Any ideas on what might be my problem.

Mike