Ditto on that advice! As long as the carb gets fuel that doesn't have huge chunks of trash in it big enough to block the needle valve open and flood the float bowl, it's a pretty forgiving system. I've raced Holleys since the early 1960's, and while they don't get any points for originality or out-of-the-box correct calibration, they're very tunable.
I believe once you radically simplify the fuel supply side of things, you can move on to getting the correct mixture for good all-around performance. Yes, you'll probably be doing some jet swapping, and possibly changing the accelerator pump cam to avoid having some flat spots and/or problems with an over-rich mixture. Holley likes to jet 'em rich from the factory to avoid the possibility of inexperienced engine builders burning pistons and valves. Almost every Holley I've ever run on the dyno needed leaning out, sometimes a bunch!
Jerry
