OK. My floats are nearly finished. Are they really too big to attach to my 4*60?

I thought good floatation, light wing loading and power (91 4stroke) would be OK. I believe the 4*60 is about 7 pounds without floats. Adding 4 pounds of floats should put them right in range. Am I wrong?

I have to admit now that the floats are about done they are large, but....