55 with charging trbl?

[carfolite]

I have recently purchased a 55 Bird. Nice parade condition. The car has a replacement engine (312) and was converted to a 12 volt system about 25 years ago. The generator / alternator looks more like a generator than the later. How can I tell and how can I check if it is truley charging. Also - how can I tell if componints like the fuel guage was also updated?
Mike in NJ