yes the 100 is more than you need. But, on the other hand the 100 s size and weight is almost identical to the 91 saito. I have also seen this plane fly wonderfully with the 91 saito. Therefore I would do it......however.....you must know how to fly this type of combo......if you try to fly it like a pattern plane or war-bird and prop it with a 13X9 13x10 12x12....the motor will pull the plane apart.

if you use a low pitch large diameter prop ...fly slow and let the torque of the motor muscle you through the maneuvers at low speed I think it will work fine......