Being a former owner of a 67 Fury convertible (C-body) I can tell you that
you're biting off more than you can chew. For one thing the rear quarter
windows are nothing alike between C-body hardtops and convertibles. You'll
have to find a set from a parts convertible, but then if you can find a parts
convertible wouldn't it be easier to simply restore it using parts from your
hardtop. I'm not saying the conversion is impossible, but it will require as
massive tear-up of your hardtop to fit the convertible parts. In the end, you
will have spent more than if you simply found a dilapilated convertible and
restored it. I recommend that you give it serious thought before you put your
torch to your car's roof. Bye for now.
Doug
58 Crown coupe (was born a hardtop, and will remain a hardtop)