I used to have the same starting problems when I used a 750 DP Holley on my 360. It was a fine line in giving it enough fuel to start without flooding it. My cure was to buy a QuickFuel Hotrod series carb. It is a 680 c.f.m. It comes with a electric choke,(which I have never hooked up). It has vacuum operated secondaries, which make it much harder to flood. It has worked well for me.