Floats are not pre set however they are normally pretty darn close. The top of the float should be parallel with the bottom of the carburetor. that is a great starting point.
Replace your float needles as well. Hone the float needle seat with a small piece of Scotch Brite wrapped around a screwdriver and a little squirt of WD40. Make sure to clean it with carburetor cleaner and a little air when you are finished.