Overcharging Help needed (74 scamp)

S.O.S. ok folks here we go. so i have a 74 scamp with a 318. i have a new napa alternator and and a new battery and a new volatage regulator. yesterday i put a new voltage regulator on and when i hook it all up im getting 15 plus volts inside the car and at fuse panel mean while only like 12.38 volts at the battery . when i unplug the new external regulator it drops back down to 11 plus volts in the car. honestly at a loss here .i have a dual field alternator. one goes to to the regulator the other i have tied in to the igniton wire on the regulator and bypassed all the way to the ballast resistor for key on run hot. i know im a dumb redneck but at a loss and about to set this car on fire haha. very frustrating any help would be greatly appreciated. just got the engine running awesome and running good now dealing with this issue of over charging and battery not charging . just frustrating. so thats where im at folks thanks for looking .