it has been my observation that there is no real way to maintain a
building's itegrity while insulating.  Most insulation methods prevent
the intended "circulation" of a historic building.  We have all seen the
"peeling" building, where the solution is to remove the siding, because
it was "defective".  My only recommendation for keeping warm in a
historic building is not to buy one on the first place.

Oh, and there is no justification for vinyl over historic material.  none.

Forever opposed to vinyl,

Rob