look at [link=http://www.3dhobbyshop.com]3D Hobby Shop[/link] - they mainly focus on electric planes, but have couple that would suit your needs. The 57' Sukhoi would be great for the .82 Saito or they even have a large Extra 300 SHP and a Katana that will take 50cc gas motors.

I have one of their smaller Extra 300 SHPs and absolutely love it! The planes are definitely worth looking at.