carb question (Holley)

It will NEVER run properly at TDC for initial... Unless you need to smog test it... :)

I have a 340 with a bigger cam, MUCH bigger, than that one and it idles all day long at 800rpm. Crank up the initial. You'll have to limit the mechanical in the distributor to hit your total number. Don't worry about total right now and don't drive the car until you fix the total timing issue after you have the initial figured out. I'd just grab the distributor and give it a good turn to advance it, start the car, if it doesn't kick back on the starter, turn in some more, shut it off and start again. Do it until it drags on the starter.

Long cranking time, real dirty/black carb venturis, are an indicator of not enough initial. My cars, even with huge cams light off with the flick of the starter, no extended cranking. One exceptions is if the bowls are dry, nothing starts that way.