I think Genius' idea is where it's at. That's how I did the 1302's E36 Beemer seats. Four pieces of angle iron, and some tracks off some old seats.
Cutting the old seat frames about 2" vertical from the tracks made 'em just the right height. Now, with so much adjustment, I can put either seat as far back as the leading edge of the back seat, or as far foreward as 12" from the dash
I couldn't bring myself to drill holes in the 1302's perfect floorpans.
Yetibone