I'm pretty sure those gauge studs need insulators- - -even something as simple as a short spool cut from a heavy duty plastic soda straw would prevent a short to the gauge cluster, or a couple of layers of heat shrink tubing around the studs would work. I'd also suggest adding a short piece of fusible link wire at the battery cable connector in series with the wire going to the ammeter. It is pretty effective at preventing a positive smoke check of the entire wiring harness in case of a serious high current short.
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!