Dallas, this may help?
http://www.1968firebird.org/illustrated/conv/conv1.html

and or maybe these guys can help you out some? They have always been VERY helpful in answering questions and giving out info.
http://www.convertibleparts.com/

Check around with some interior shops and resto shops that specialize in hot rods and older cars... there has to be some one close by that is a pro?

Brett - 67 Drop Top 455!