using Zbrushes Zremesher tool seems to allow me to "retop" a model without having to recreate every single polygon. after a few minutes of experimentation i found that a bunch of the 'wasted' polygons from my morph model get retopped into better positions with no loss of detail. with a ZRemeshed model all i would need to do is minor fixes to the topology then project from the previous model onto the new.