78 xs400-2e grounded out

My father in law got a 78 xs400-2e last week and i finally got it all cleaned up and running so i thought. It blew a headlight fuse and a main fuse. So i went over today and started doing some checking and found that if i do a ohms resistance test on the fuse box from the ground to the fuse block im getting no resistance anywhere meaning that i have a problem with a bare wire somewhere right? well i pulled most every part of the wiring harness out today and found nothing that looked bad. has anyone else had this problem? if so what did you find? I only had a little cheap tester there today i didnt have mine so ill take it back when i go over there thursday to look at it some more. I even pulled the head light to make sure everything was ok in the headlight bucket.