Electrical charging problems

A 42 amp alternator is going to have some seriously low, low output at idle, especially at 600 rpm..

Actually the original 46A squareback, so I'm talking about "as Chrysler produced it" and not some pirated, mexicanated, chineseoated "rebuild" puts out better at low RPM than some of the larger rated alternators, and absolutely better than the older roundbacks. In other words the output curve is not linear.