myself,I would go with the single wire alt that came on it,then upgrade the points style VR with a soild state replacement they have for them

made a world of diff with the 68 Dart,fixed the discharge at idle with the light on,and the amp gauge stop jumping around and was steady across the gauge sweep after that

uping the amps is not a good thing on the older sytem like that,imo

unless you bypass the amp gauge and up the wire to carry the extra juice you will have with a newer alt