An extra 15 amps of charging current is an advantage, no matter how it gets there- - - -generator or alternator. There are several 12V D-R generators on Ebay today, advertised as "45 amp". "Buyer beware"- - - -do an online search for the part number to confirm the capacity. Your present regulator can be adjusted to make use of the extra capacity- - - -no need to replace it. PM me for a phone number, and I can talk you through the adjustment procedure.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!