When I got my 74 Pantera L, the previous owner didn't mention it had a driver's dropped floor (I didn't see the car up on a jack). When I sat in it, I just noticed that the pedals and steering position are not bad at all and for my size of 6'1" and 240 lbs, I am quite comfortable in it with a couple inches of head clearance (I have a taller torso and shorter legs compared to guys my height so I have problem with headroom and not so much with legroom) and the driving position is great. However, it was a totally different story when I sat on the passenger's side. To start with, getting in was much harder with my head hitting the roof pillar and the leg position being way to the left and my head stuck to the ceiling, totally uncomfortable, but it's fine for my wife of 5'7".
Later on up on a jack I saw that only the driver's side has a dropped floor. I guess his wife wasn't too tall either.
Also, I have never scraped the floor pan on anything including one time not seeing a speed bump and going over it at 30 mph (ouch). At first the seat didn't seem to move forward, but one day when I played with it's handle, it moved forward just fine. As a matter of fact, due to my strange body, I have to sit with the seat two inches forward, just putting on the seat belt with my fat stomach is a bit of hold your breath while doing it thing due to the seat position being 2" forward now (I didn't have this problem before I pilled the seat forward).
So Pantera Lover shouldn't worry. Sorry but I don't know the manufacturer of my dropped pan. Here are a couple pics including one clearly showing the dropped floor at night, parked behind Scott's yellow Bad ass Pantera.
BTW, do you like my cup holder?