Can you take a picture of the terminals on the alternator ? I've setup a Ford 1 wire and I got mine to keep functioning. You just need to lead 2 wires into the old voltage regulator connector. I don't know what terminals yer alternator has on it but I'm sure they all have the same outputs somewhere.
Not sure about tyhe voltmeter but if you want the Amp meter to work the large Lugged wire on the starter solenoid has to be still hooked up. That is the way it is on 69 but maybe not on yours.