I think you could get away with standard (< 50 oz) servos for all your control surfaces. Since you say you're not looking for high performance your control surfaces won't need a great deal of deflection, meaning you can set up your servos for maximum leverage. Also, you won't be moving very fast, which means less load on the servos. You don't need a whole lot of torque.

Anyway, 90 oz/in on the elevator is definitely overkill. More torque won't hurt though, so if you feel like spending the cash...

Also, I'm by no means an expert, but I think your control surfaces may be a bit too big for this kind of airplane. I'd think ailerons/elevator around 2" wide, rudder 2 1/2" or so. I'm sure someone more knowlegeable will chime in. 'Course if the plane's already built, never mind

Chris