Mooso,
I put the same Fiero seats with the speakers in the headrests in my '74. I cut off the lowest point of the bottom seat cushion (between the seat rail mounting points), and used Recaro seat sliders only. This put the seats so on the floor that I had to use spacers in the rears just to be able to move the seat with a bit of difficulty. I did this years ago, and if I remenber correctly, the amount of cushion I removed was about 2" or so. What a difference it made! This part of the seat cushion actually looks like a sump, so I removed that sump entirely so that the whole cushion was roughly the same thickness. If you were to make this modification to your seats, it wouldn't affect your upholstery at all. I'm 5'10" and I have stock floor pans and a 13" LeCarra steering wheel. I've got what I consider to be a goodly amount of headroom for a Pantera (about 2"), and no leg/wheel issues at all. The seats are more comfortable and supportive than stock, and I've driven for hours at a time in them. Maybe you could try this before giving up on a nice set of seats. Hope it helps.
Michael
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