Did a similar construction using a seat from a Mazda 626. Kept the mechanics under the seat so it's adjustable both in hight and length and the back is of course also adjustable.
This way I can use a more upright position for GT and TouringCar racing, and if I feel like it, tilt the back and lower the seat for that "open wheel" feeling
THX. I didn't find Type-R seats, some Sparco seats are available in our country. But costs about 200euro I'll try to find used one, I don't have so much money.