The Funtana will fly just fine with a Saito 80. I have a Magnum 91 four stroke in mine (because that is what I had laying around)and the plane rockets insanely vertically. From what I gather from all the posts on the subject of a Funtana engine, anything from the Saito 72 to the 100 and everything in between will work. It all depends on how much you want to overpower it. If you are flying in higher altitudes I would lean towards the higher displacements. If you are near sea level, I would stick with the lower displacements. One advantage of using the saito 72 is that you don't have to make any modifications to stuff the engine under the cowl. With bigger motors you have to modify the existing motor mount or redrill new holes in the firewall to widen the motor mount beams to accept the bigger engine. I know a few others who have Funtanas powered by the Saito 72 and they have no complaints. Again, it depends on how much overpowering you are comfortable with and how aggresively you plan to fly the airplane.

Good Luck,
Ken Pavlou