Get rid of the generator and the voltage regulator. Put in an alternator. There are a whole bunch of grounding issues, adjustment to gaps on reg., old wiring, old generator brushes, winding problems and etc., which are much less of an issue with an alt. Search in here how to swap, it's not hard.
If not,
READ THIS:
http://www.netlink.net/mp/volks/htm/gen.htm
This guy says 35V output, my 55-59 GMC manual says stock Delco Remy gen is 14V output at 2780 RPM. and 25 amps.
Gen part no. 1100304 (V8) or 1100336 (6cyl). There were optional generators available. If you want that info, give gen part no.
Those "Tell Tale" bulbs do come on at low RPM and go off as you drive.(increase RPM) That is normal. Should go OFF at high idle and above.

Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn