Regulator MUST be grounded, and I mean to "same potential as battery."
Here are the issues:
The solid state VR's used 70 and later are TEMPERATURE compensated, and that means that you must check them after things are warmed up. If you get into section 8 of the manual, somewhere in there is a chart showing that. The "go to" warmed up (with battery stabilized) running voltage is 13.8--14.2. 14.5 should be livable
The VR MUST be grounded, but that does not mean that the body/ firewall is well grounded to the battery. I Look at the pass. side head. Those bolt holes on the front of the head are also on the REAR of the driver's side head. Buy a Ford starter cable, 1'--1 1/2' or so, bolt it to the head with a short bolt (be sure not to bottom it) and bolt the other end to a good point on the firewall. You may have to drill a hole and bolt it, star lock washers. Another place is often the master cylinder mount studs.
The ignition "run" line normally dark blue which powers ignition, the VR, electric choke if used, etc, often has VOLTAGE drop in the harness, and that causes over charging. Common points of drop are the bulkhead connector terminals, the ammeter terminals, the ignition switch connector and right in the switch contacts themselves.
Again, 14.5-6 is not bad