Thank you for your prompt response. I had read your article previously and, have now reread it, I wish that I had read it prior to the initial insulation.
I think that the exterior insulation is not an option. The closed cell spray foam was proposed by a local insulation company and probably will be our choice. Should we stay at a lower R-level? R-10 seemed to be suggested in a couple articles, what is the trade-off between higher R value? Was the placement of a second vapor barrier, perhaps sandwiched between our current drywall and new drywall a non-starter?