go to
www.kangkeusa.com and check out the F3A40. I have been flying the snot out of one for about two years, and it is a really nice flying airplane. I know it is supposed to be a 40 size plane, but I have a GMS .76 on mine, and that is a good match. Your ST 90 would be perfect. IMO this plane is too large and heavy for a .40, but flies great with a bigger engine.