We are moving in to a new house that's very builder grade. There are several pass through doorways off the living room that were simply drywalled and bull nosed. I'd like to frame them out with molding. My question is do we need to remove the drywall back to the door frame or can we apply the wood over the existing drywall.. I'd like to do more of a craftsman style frame out with maybe 1x 4 or something wide.. Any suggestions would be appreciated.. Also if drywall is needed to be removed how far back so you cut it?