I had an old brass float get a pin hole in it once, at that point it was a brass sinker. It was flowing fuel out the vent tube so fast you couldn't keep the engine running. I ended up adjusting the float down to the point the needle was closed with it sunk, and got home to diagnose. Used it as an excuse to put a notched rear flow in with jet extensions, came in handy when it got faster. That was about 25 years ago. I also had one where I got a speck of something in the needle and seat that left it stuck open. Had to clean it out, problem solved. Overall I have had great experiences with Holley carbs over the years, when built right, and most of mine were used. The only Holley carb I didn't like was the 770 truck avenger, that thing would idle on an incline but with no high speed air bleeds the fuel curve was way off with no way to fix it, not a good compromise.
But I agree, if someone worked on it with a drill more often than not it's messed up and its not worth trying to fix.
Holley carbs are so adjustable they dominate racing and its the only carb I'll use. Although at this point I don't really want to mess with them anymore since you always have to drain the fuel bowls and make a mess to change jetting, etc. With EFI you just make some changes with the laptop or tablet screen, etc.
I think you will like your new engine setup when its all done.
