Holley Flooding Engine and Spewing Gas

Dont reinstall the old parts.

Do all final float settings on car running. Get the fuel level adjusted ,with sight plug out, to the bottom of the sight hole and tighten it.
If the floats are even good, check them for being filled with gas.
Let the idle speed screw out till the blades have closed...then open them about 2 turns...or until you see the throttle blades exposing about .020 of the tiny slot in the throttle bores.. you'll need to do it before carb goes on so you can look underneath to see this. HOWEVER..Technically if the floats are good, needle and seat work properly...NO LEAKS it should fire up and run on the mains , at least, even if the idle speed setting is too high... flat out it should at least run to do the idle adjustments and so forth.
Are the secondary blades closed enough?
There is a little flat head screw to set those from the bottom of the base plate.