340 carb size?
3310 Holley,sweetheart when tuned.
I don't think I have heard a better quote.
Throw a quick change vac spring kit on, add electric choke if needed for cold weather.
Tune it right and run it.
Parts are cheap, and I guarantee Holley will still be manufacturing them when I am 6 foot under.
As for your float problem, it most likely is just a needle and seat, buy a refresh kit for like 40 bucks and rebuild it your self, Holley has how to videos on their web site.
There is several excellent Holley carb books that can be bought used off Amazon cheap, buy one and learn it.