[Charlie Stephens]

If you decide on an original (or a repro of the original) run two wires from the output of your alternator. One goes directly to the battery and the other to the ammeter. Use each wire heavy enough to handle the entire current (see google). This will protect you in case your ammeter fails open (I hate those repro ammeters). Try to make the wires about the same length. Now only half of the current will go through your ammeter. If you can't remember put a big piece of tape on the dash and write on it "Double reading shown on ammeter". I doubt your alternator will put out 30 amps. If it does the belt is probably too tight and you will be wearing out water pumps.

Charlie Stephens