The simplest solution to an over sensitive elevator is to reduce the elevator throw.

Reducing the horizontal tail area by 20 percent will move the neutral point of the the whole plane forward. This will require that you move the CG forward to achieve the same stability that you had before. The smaller horizontal tail will also result in a reduction in pitch oscillation damping so that the new configuration will not be quite as groovy in pitch. The pitch damping can be improved by about 24% over the original design by lengthening the tail moment arm by 20% even with the smaller horizontal tail. The location of the neutral point will be restored by the longer tail moment arm to compensate for the smaller tail and the original CG can be used.

The roll rate will not be affected by the changes in the tail length or area. The wing's stall characteristics and CG location have a lot to do with how the plane spins. A more tapered wing planform and and lighter wing tips will improve the roll rate as will larger ailerons. A more tapered and swept back wing planform will increase the tendency to tip stall and make spin entry easier both upright and inverted. The sweep back comparison should be done along the wing's 25% chord line for a valid comparison.