There are two kinds of voltage regulators- - - - -Delco-Remy, and WRONG! Look on ebay for an original equipment Delco- - - -there are plenty of them there, and they're not terribly expensive. Any 12V negative ground Delco will work- - - -don't worry about the supposed application. Even a heavy duty regulator like an Olds or Cadillac can be adjusted to work with a Chevy generator. The only difference is the adjustment of the current regulator.
If the generator is charging that well, it's polarized! There is no such thing as polarizing a regulator.
Jerry