Helping my son with his 78 camaro. seats were toast so he bought a drivers side ProCar seat, which also meant he had to buy the floor adapter thing. Had to use the lowest hole on adapter (which also meant we had to grind off part of the mount), so it is as low as it can go, and still my head hits the roof. I am 6'4". I seriously do not know ho people get inside this car?? steering wheel is so low? Like I have to contort and do yoga to get in.
Seat is as far back as possible, then I also can tilt the seat back a bit which helps. But that is no way to drive. So are these ProCar seats higher than the stock seats? Or is there something else to consider? I see online some extender brackets? which says gets 2 inches further back? But it would also raise the seat 1/4inch due to bracket? Any thoughts here? We do have a seat from a 76 that could be reupholstered but afraid that it too may also be too high?

 

I'm thinking those seats are taller.

 

I am 6.1 with short legs. In high school I had to custom make brackets in my 1974. The factory setup had my head touching the roof. In the third/fourth gens I had to tilt the seat way back.

Set the seat in there with no mounting bracket “sliders” level it will some wood. See if it fits you then. Then just make some brackets the hold the seat there. You lose adjust ability, but you can gain 1-2 inchs. If you use the original mounting holes, then you can just reinstall the sliders as needed for others.

This is very commonly done on budget race cars to clear helmets. If you want to spend the money to do it right pick a chair you like and call the manufactures rep.

 

Im 6"2" and I have no issue in fitting.Maybe because its a"T" top car. Thats with both factory and Corbeau seats .It would probably a seat of custom seat mounts and frame would work.