It sounds like you have multiple problems.
First, check the carb for fuel leaks down the manifold. You should not see any fuel discharge while cranking (except for the accelorator pump momentarily when you open the throttle. The float level may too high, bad float valve, etc. Hollys have, or had, a bad habit of blowing the power valve on backfire that can cause problems. Check that too.
Second, get it to crank reliabley. Not start, just crank. Take out the plugs, disable the ignition and crank the thing to blow any fuel out of the cylinders.Once you know it cranks reliably, if it stops mid-crank you will know it from the ignition trying to fire at the wrong time and can concentrate your efforts there.
Third, diagnose any ignition problems. Firing order, timing, primary wiring, and so on.
Be methodical and check each system one by one. You will waste a lot of time jumping around playing whack-a-mole otherwise.