NOS carburetors. What issues to be aware of if any?

My one and only experience with a nos was bolt it on and go, no problems. Put a nos carter 2 barrel on my 318 '79 power wagon over a year ago and great thus far.
Have owned the truck since new, probably had at least 3 re-built parts house carbs on it thru the years. This one seems to be the best, don't remember exactly what went wrong with the original, probably ethanol gasoline, which I do not run in the truck anymore.