Ammeter to Voltmeter...who does it?

No, the original ammeter wires are "hot" all the time, so the voltmeter will sit there, always on, and cause a battery parasitic drain

You need to connect it either to "ignition run" (not fused) or in the fuse panel a switched wire on the accessory buss. Stay away from the fuse at the end of the box, INST, which is for the dimmer controlled dash cluster lights