Johan made a '68 Fury III 2 dr. HT with a different roofline, and they still occasionally release their old '68 Fury I police car. The original '68 Fury coupe/convertible was only released in 1968 as an annual kit or promo, so you'll have to search the collector market for them, try eBay.
For the Sports Fury, you'll need a roof from a Johan 1968 Chrysler 300 as well. Good luck w/the project, they're neat cars and somewhere in the last 10-15 years I've seen a picture of a model someone made of a Sport Fury, and it looked great. You may get lucky and find a promo w/a damaged winshield frame relatively cheap (though never inexpensive), and then graft the entire roof from the Chrysler.
Here's a ratty looking one I've got to restore some day:
Here's the Chrysler 300 like you'll need for the roofline:
