You have many files to update. You correct in your assumption in db.c that load_zone() will need updated, and so will reset_zone().
You will also need to update zedit, oedit, medit, and trigedit off the top of my head.
Several Header files will need updating, db.h, oasis.h and so on.
This is a very basic patch with several variations out on the legacy circlemud.org site, and i am sure there is one or 2 here. If not I know i have it saved somewhere.
Matter of fact, i will just create a patch file and upload it. If Rumble wants to add it to the next release great, if not, this is really not needed for a BASE code.