I'm doing my '57's floor with steel supports and aluminum flooring. I've done a few other cars this same way and the floor comes out strong and light, best of both worlds. Granted, it's a lot more work and more $$$$ then just welding in a sheetmetal floor, but for me it's worth it. I'll also make my tranny tunnel removable in the bellhousing area, sure does simplify clutch adjustments! No back seat going in mine, but there will be a flat area nicely carpeted so my dog has a nice place to ride!!!!!!