Put together some picture information on the 70 amp bus alternator. Pictures show what is involved in using one. It takes a different fan (you can use your smaller one), a large hole plastic cover, different rubber boot and face plate. You can use your stock alternator harness but the rear plug will be uncovered. Original style with molded plug is NLA. Parts to put package together are nearly impossible to find. Best option is to go with up rated 75W stock alternator.
FYI: Plastic shield has to be installed BEFORE the fan/pulley goes on