My thoughts: If you are not sure you can contour a neck profile then taking a fretboard off, making a tenon and then fashioning a heel and then gluing on a new board, leveling it, fretting it, and making it all line up with the bridge might be an advanced mod and it also seems like working harder than smarter. Just make is a short tenon set neck. If you have a tight enough fit and enough meat on the sides of the cavity then you will be perfectly fine.