Great info !

I wonder what the difference in the generators is that they used different regulators . I wonder if you can mix the generators and regulators that are listed there

The main difference is the potential output of the generators. You need to check the specs as to maximum amperage, and have a regulator and generator matched. 1954 generators were 45 amp outputs, whearas 1950 for instance were only 30 amp. If you had a 45 amp regulator paired with a 30 amp generator it is going to cook the generator, unless you reset the maximum output by reducing the spring tension on the current coil. I have a new regulator here for $60, plus postage.

$60 NZD ? and is it the vrp-6002a regulator ?

It's an Auto-Lite replacement regulator, not OE.

Found a regulator locally - thank you !

Question - if it was attempted to be used as negative ground , is there anything that I need to repolarize ?

You must check that the regulator is negative ground. Otherwise the points will burn out.