1/4/14:  The rear firewall has several steps to prepare for carpet and upholstery.  First, I fabricated a 1" roll bar that runs above the window and is welded to the chassis at both ends.  I'm sure it doesn't meet code for race cars, but I hope it is better than nothing.  I sure hope I never need to find out!  Next, a 3/8" piece of plywood was used to create the main firewall panel.  It runs from the top of the roof to just above the top of the console where the rear speaker enclosures will set.  The rear window will also sit on top of this rear panel.  Layered around the window will be a removable trip piece of upholstered trim (pic coming).