Reply to "How about this one?"

Wannabe, as far as the dropped seat pan(s) reducing chassis stiffness, there are two general ways this is done. The first is to cut the stock pan on three sides (not on the front) then bend the cut piece down in the back so you have a sloping steel pan. Then you fill in the 3 openings with sheet metal. The other way is to buy or make a formed tray, cut the stock pan completely out and weld the new pan in all the way around. Both methods work.

Just ahead of the stock seat pan is a stamped stiffener that runs crosswise to the console. This stiffener is sometimes cut out to allow a longer cut pan. The driver's seat can then adjust forward or back a tiny bit, assuming you mount the seat on the stock rails (many do not).

I will say this- it's very difficult to drive a Pantera competitively when your head is jammed up against the roof and your knees hit the lower dash, both due to mounting Recaros or later factory seats with over-fat seat & back-cushions. Given a choice, I'll take a slight flexing....