When I rewired my 56 last year using the American Autowire Highway Series, I was faced with the same issue. I called their tech support and was told NOT to use the ammeter. The reason they do not address the issue is that they felt the ammeter would become the weak link in the system, especially if you start adding modern electrical loads like stereos, and such. I switched to a voltmeter instead. You might want to call and talk with AA tech yourself before you try anything.
