Wiring an ammeter is ridiculously simple. It takes a huge amount of help to misunderstand it. Run one heavy wire (#8) from one ammeter post to the battery cable connector at the starter. Attach EVRTYTHING else- - - -ignition switch, power to the fuse block, headlights, AND the charging wire from the alternator to the other ammeter terminal. Absolutely NOTHING could be simpler. If the ammeter indicates backwards (- direction with the engine running) reverse the connections.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!