Lawrence,
The car looks great! You're doing a fantastic job! One thing to note on vinyl top cars. That seam was not leaded. It was filled with a very hard, yet pliable, caulk. This would trap moisture and swell over time causing the buldge you typically would see. Non -vinyl top cars got the lead there. Is there exception to this? Of course, and I restored a 68 R/T with a black vinyl top that was leaded. But... the few exceptions are not the norm. Nobody uses that caulk anymore, obviously, and it's best filled with USC's Allmetal in the leaded joints.
I'll shoot you an email with some more info.....
Cheers
Dave