Do what Ed says. He is smarter than the next three people you know, combined.

Also possible sources for floats: Sea Commander and Slocan Floats. DO NOT use built up plywood floats as they are much too large and much too heavy.

You will find that a Kadet Senior is a fantabulous floatplane. I have seen them fly with a .45 2C thru a .90 4C. My son flies one with a .70 4C Magnum and it is about as ideal as it gets.

PlaneFun Floats offers "narrow" floats to address the light weight of the Ksr. I am sure that Seaplane Supplyhas an appropriate option.