charging system issues

ok on my 74 dart I have some charging issues.
sometimes the volt gauge will peg to full charge, then after a while itll go back down to normal. a couple years ago I had it burn the battery wire stud right off the alternator on a road trip. got it replaced, but it would still peg out at full charge on my way home, so I would pull over and disconnect the voltage regulator for a while and keep going. ive read about people bypassing the factory volt gauge, will this fix my problem? any diagrams on hw to go about doing so?

also on my 5th ave I'm trying to save weight and want to do a denso alternator swap, since no one on the f/j/m site have done this, what year/model Toyotas will work? also is there a wiring diagram for the Toyota pig tail?