Hi Bill
Do you want to modify it to move the seat back further than the adjustment will allow?
I imagine you would have to extend the front of the tube frame of the seat itself so it continued to sit on the rollers, or you’d have to fabricate some metalwork to move the brackets with the rollers backwards. Both sound a bit complicated but all things are possible. I know of one car in the UK that has Rover 2000 seats.
Chris
Chris