No doubt the fusible link has failed, no wonder with with all the heat, motion, dirt and moisture affecting the wiring down to the starter. My 62 had no such problems because the body wiring went to a big battery terminal on the fender, only 2 very heavy wires continuing down to operate the starter. It was also far easier to service the starter, just unbolt the 2 wires on the fender and drop the starter with those wires still attached. I believe we can thank bean counters for eliminating the upper terminal and dragging all those other wire (with their fusible links) down to the main starter terminal. After struggling with these problems a while, I decided to go for the reliability and convenience of the fender battery terminal. Here is a picture of the conversion on my 77, just cut the starter cable at a convenient point and rewire. The body wires are pulled out of the muck and stress at the bottom of the car, note fusible links making connection. Changing a starter is so much easier when it does not involve wiring while balancing a heavy starter on one hand. Bruce Roe
You were all correct, the fusible link was the issue. Got it replaced today- not an easy job. Happy to report that the Skylark has power and runs again!