had to have a ground right at the meter for that wire to fry, not at the starter - excess current was running there, where there should have been no ground possible with the key off .... did you have the heavy paper insulator under the terminals of the gauge? may have been happening for some time but never long enuff to notice cuz of disconnecting the battery
helpful hint - after doing electrical work [like a new harness] as discussed in another thread, connect the ground first, then touch the pos cable to the battery post and
watch for any spark ... if seen, find the problem without letting the smoke out

Bill