Andy, those tops were done aftermarket in Cal. I can't remember the company's name. It might be easier if you may try contacting, Toyota Motor Sales, USA. They were all done in the Cal. port of entry. The other thing you will notice about the car , due to rear wheel drive, is the "body shake." It's a viberation to extreme, that you will feel through the steering wheel. Mind you, it's nothing major, it's just there when hitting bumps and such.
The car wasn't designed by Toyota to be a convertable. Not that Toyota didn't sign off on it. They just had to restructure the frame under neath to make up for cutting the top off.
Still a great car and a classic find. You will have a lot of fun with it!! Plus sentimental value. TJ
P.S. 1985 was the first year of the convertable.