im guessing due to the lack of floorpan you are starting from scratch? modifying the sierra tunnel?
what front suspension are you planning to run? mini suspension with 9" Wide wheels could be interesting to get the handling right? i would think it would be easier to start from scratch with the arms, sticking with the double wishbone type setup and coilovers using the mini hubs and custom shafts? or like the thread above just go for a typical sierra type set up with sierra or custom hubs?