Your enlightment was cheaper than mine.

I had a 73 with that tear, and tried to fix it first with bondo/fiberglass, and that failed very shortly afterwards. Then I put new sheet metal in, and it failed. That's when I took it to a body shop and got the bad news. The car died a quick death in 1987/88 after a hurricane went through the Tampa area and shot a phone pole through the rear quarter.
I also saw a 73 with that tear that was for sale for years by different owners in St. Mary's County, MD. It was yellow with a black interior. It would be for sale in a yard for a few weeks, then disappear until the new owner figured out the car was a basket case, then it would be for sale again, disappear, be for sale again, and on and on.