I used seats from a Honda Civic in a Volksrod project. The headrests were removed from this car but could stay for a Puma. The seat track mounts were easy to modify to fit the flat floor and they were small enough to work nicely.
The seats I will use in my GTC came from a C series Mercedes.
Further seat info. The Mercedes seats are too wide in the shoulder area for the convertible top mechanism on a GTC. I have now swapped in some seats from a Mazda Miata, They fit well.
The original factory headlights are still installed on my 81 GTC however the shells are rotted and unusable. They are CIBIE "Super Bi-Iodo" headlights with the horse logo in the center of the lens, which according to the markings on the light were manufactured in Brazil