I need to install a new lockset into a wood door that has an older, larger mortise lock. The old lock is a much bigger assembly. It's about 5" tall and extends about 3" into the door. The new lockset is two pieces, both requiring nothing more than about a 3/4" diameter hole drilled in from the end, with the usual 2" through-hole for the handles. What's the recommended method to "fill in" the space consumed by the old lock assembly? And, no, I do not want to get a whole other mortise assembly, or rebuild this one. I've had my fill of these style and have already obtained a new lockset.
Is there some sort of kit for this type of retrofit? Or do I just carve myself out a chunk of wood to refill the old hole?