All my electrical woes.

The ammeter is totally separate from the rest of the cluster, just 2 dedicated posts. I am preparing a post on how I upgraded my alternator and kept my ammeter.

In my 65, the radio wiring was a separate "add-on", dedicated wires (red & org I recall) that "daughter spade" off the fuse box and run straight to the radio (end in a 2-wire 57 terminal).

The fuel and temp gages work off a 5 V regulator that in your car is a small metal can plugged into the back of the cluster. If it has failed, no big loss since you can get a much better electronic version for ~$25 on ebay. Order it w/ spade lugs and it should plug right it (3 wires). You stick it on w/ Velcro. The fuel gage can get burned up easily, but I think the temp gage is pretty robust, so likely it is your Vreg or maybe just the power to the cluster. I don't know about the oil press gage.