Grossly overpowered = grossly overweight. You'll have to reinforce the landing gear block and firewall. Then you're going to have to find some oversized gear to give you enough ground clearance (I had barely enough with a 14X4W). Heavy torque servo on the rudder...
That Saito 100 is just barely going to be enough to fly a .90 size plane, according to the folks here, you're going to need a 1.60 - 50cc for that. I have found that overpowering and an overweight plane doesn't fly near as well as a lighter more nimble plane. I'd go with the .82.