or can a bad voltage regulator say put out to much juice and fry it?

Not really. The regulator is the control valve for the letting power flow through the rotor.
If you have an original type, under the cover you'll see a set of points and some thin wires. The wires are fusible links.

If you have voltmeter or a one of the better battery chargers, check battery voltage when the charging is complete.
Some chargers will show charging current. Pretty much the same as the one side of the ammeter in your car.
It may draw a lot of current initially, but for long deep discharge, that needs to be reigned back for a charge at low current.

if you have doubts about the battery, bring it somewhere that can put it under a load test.