Floats are a bit too long. 70-75% of fuse length of 46 should be 32-34in.
However your'e stuck with them for now. Check the angle of incidence of the wing to the floats. Put top of floats level and if you have an incidence meter on the wing make sure it is 1-2deg. pos. Also make sure the floats are mounted securely. If the can act like the are independently controlled both up and down and side to side[very wobbly] this can also lead to weird take-offs. It could also be too heavy. You state step is 2.5 in. behind leading edge. not familiar with the a/plane. Step needs to be on or very close to balance point of the plane. Squirrelly in pitch[up and down]? sounds tail heavy to me. Make sure you check the balance.Just a few thoughts,
Cheers, Dave.