I am 6'2" and use a slightly modified '71-'72 three piece seat (new upholstery and the seat-back attach tabs slotted). You 'rake' the seat for a slouched position. I wore a helmet in this car for years while autocrossing and open track events as well as 5-hour drives.
Even larger humans or those with exceptionally long legs have remounted the stock pedal mount plate in the front trunk as much as 2" forward of the stock position, or eliminated the seat adjustment rails. Dropping the seat pan as was done in stock post-Ford era Panteras helps. Avoid thickly padded aftermarket seats such as Recaros.