LFM620

Hey guys I have a problem with my 1973 Datsun 620 I bought it and pervious owner put a z24 engine in it and those have a internally regulated alternator how do I wire it up to the 620 harness my ground is on the motor mount I think that's a bad place have the power going to the starter post I need to know where I need grounds and how to wire the alternator to the 620 harness it completely drains the battery right now.