Finally gave up with floats on my "Sky Arrow".
After many attempts I could not resolve the nosing over problem so I took the floats off and installed wheels. Perhaps if I used 27" floats instead of the GWS 21" that may have solved the problem, by extending more float area in front of the nose. It's been an interesting engineering/aerodynamic challenge but at least I'll finish the flying season in the air instead of in the water. Modifying the aileron lenght and using the remaining portion for flaps, increase lift was significant however.
Don

Generally, the floats shouls be out in front of the nose. Looks like yours are about even with the nose

You are right, and I had considered that, however when I was at EAA's "AirVenture" this year I saw a Sky Arrow and a Challenger, also a pusher. Both planes floats did not extend in front of the nose. Here's a photo that makes the point.
I was told that the reason for having floats extending in front is to keep the prop behind the water spray, on tractor planes. With pusher planes this is not a problem.
I think having longer floats in front of the nose would have prevented nosing over.
Thanks for your comment,
Don