RE: LT-40 on Floats-No go!
Soloflyer,
Jack up that 40LA and replace it with a 60 or at least a hot 46FX.
My Avistar with the 40 would get on the step and as soon as I applied up elevator for take off the rear of the floats dug in and the water rudders drove a stake in the water and slowed the plane enough it wouldn't take off. In calm water it wouldn't take off but I could nurse it off in choppy water. A Tower 46 solved the problem.
The 40 LA is a fine engine, I have several. But, IMO, you are not going to like your LT40 as a float plane until you get more power on it. If you have to buy an engine, take a look at the GMS 47 or 76. I have the 47 and it is a sweet engine and powerful.