How are you determining that the float isn't working properly? Does fuel run out of the overflow? Or do you just feel the carb is flooding? Take a piece of clear tubing about a foot long and attach it to the overflow tit on the bottom of the bowl. Hold the tubing vertically along side the bowl and open the drain. The level should rise in the tube to slightly below the seam of the bowl and carb body. If it does go higher, you do have a float problem. If it doesn't, then maybe you have a split in the overflow tube. Not uncommon by the way. They are sometimes hard to see, but if you remove the bowl and fill it with fuel, and it leaks from the bottom, you have a split tube.
I think it is even possible to install the floats upside down. I can't remember what bike I was fooling with, but I got one in upside down. Didn't work well.
If you have swapped around a couple of needles, and dressed the seat, I'll bet that it is something else. I assume the floats "float"? I haven't heard of a case of sinking floats since they went away from the brass ones.