sigh... the float height.. and the float valves. THe floats are old, and can bind in the bowl. The float gauges are home made using a ruler, so they are up to you to get right. Other than that, they are easy to rebuild. I have had 3 different 73-76 banks, and each one has one carb that leaks past the float valve...
if yours doesn't leak/overflow/flow to wrong level, thank your lucky stars!
michael