ed, i make my face frame sides 1 1/2" inch, the bottoms 1" wide, and 1" between drawers (for base cabinets). for sides where they meet another cabinet, i leave the face 1/16" proud of the side, it ensures a frame to frame mate. check the mating wall for plumb and straight with a level, that should help you with overhang for scribing, add that overhang amount to the 1 1/2". you may need more overhang if your corner is not square. the exposed side you can leave the frame proud, then router it off with a flush bit.