You have the right idea now, go get in a Viper with adjustable pedals, you will be surprised at the room, but I promise that when you get out on the road for your test drive, you will feel very bad about waiting so long to get in one!!
I am 6'5" and have a '97 GTS, I originally planned on getting a seat lowering kit, but once I put the pedals all the way back, seat all the way back, there was no need for the kit. Although, Dirk hit it on the head with the problem with stretching out. The only place for your foot is behind the clutch. Maybe a lowering kit would help with that?
Please let us know how your first test drive went. And please, please, start slow on your test drive, this is a Viper!!