i have a dle35 on my lanier tcraft and it would be fine with floats. g26 would be a bit anemic.. you dont need the extra fin. i have several cubs on floats both with and without the fin. the one with the fin will come out of a spin 1-2 turns sooner than the one without.
DO NOT DO THE 4 stroke.. i dont care what the paperwork says you will have less power than the g26...