I parted a '73 late last year, had its original vinyl roof, and it had 2 seams. Here is a pic of an original '73 roof I found archived . I have been down this same road. After the company sent me one with 2 seams, I thought I was all set, WRONG. The seams were for a Tempest body and were near the drip edge. You need the measurement between the seems to verify this. I wish I had those for you.
