Make sure the base of the regulator is grounded to the engine. I've cured several charging problems by simply running a ground wire from the regulator body to the alternator case. When an engine gets swapped, it's not uncommon for the ground wires to get left off, insulating the engine from the chassis by the rubber in the motor mounts.
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!