There are bits out there that will come very close to what you want. Do you have to scarf old to new ? If not a half inch, etc. beading bit will produce a profile that can be used especially if it is linked separately within the same trim detail.
1/4' or 1/2" are almost always available if they are for a ROUTER applicaion.
check with bosch. they are found in most retail. online it's all there.
good luck
