That's precisely what happened. I'd laid the Red-Kote on a bit too thick--it doesn't really level out--and the float got stuck. The carburetor spouted gasoline like the Trevi Fountain.
So, back to the drawing board: turns out that Red-Kote dissolves somewhat in carburetor cleaner, and can be removed completely from the float with a fine rotary brass wire brush I use for some clock-repair operations. So I got it all off and now I'm trying another gasoline-proof sealant called, without apologies to anyone, as Indian Head Gasket Shellac. He's right there on the bottle.
This stuff is thinner and goes on quite smoothly. It seems dry this morning so I'll throw the coated float into the test jar of gasoline to see if it'll float for a day or so.
I should have bought a new float long ago but since one of the pleasures of an old moped consists of fixing the fool thing I really wanted to see if any of this works.