Jerebus67
I am also build ing a Convertible and decided to go with the Martz Chassis adjustable 4 link with Coil Overs. You can adjust the ride as you see fit (obviously with some limitations).
Look here:
http://www.martzchassis.net/page7.htm
Good Luck and welcome. If you are building a Protouring car, this is your lucky day, man, you've found the right place and the best guys on the net to help you. No Egos here.