Yes, you can get a float separately from a kit. In fact, when I build a Q-jet, I always replace the float. What's not available by itself is the air horn gasket. Be VERY careful removing the top of the carb, as all the fuel metering flows through the gasket between the air horn and the float chamber. If you can get a needle valve and seat assembly, change it while you're in there. Some better-quality parts stores will have the needle & seat available separate from a repair kit, especially if they happen to be an AC-Delco parts distributor. Be sure to set the float level to the correct specification.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!