edmoor,

You may find some guidance for re-design here:

http://users.mo-net.com/shirl/Design.html

There is a practical relation among wing surface, stab surface, dihedral and vertical fin surface.
Deviations from that relation may cause problems with roll control, like Dutch roll or spin instability.

If it is marginal now, you also may need to increase the tail area, or the control surfaces of the tail for the new wing.

Not to be scared; I recommend replacing the wing and test fly it; then, making small changes as needed.

Be aware the original CG will shift after replacing the wing; just use an on-line CG calculator.

Regards!