I can think of 3 Fj with racing seats off hand
1. Donahoe Racing Class 3 Fj (my favorite Fj ever, just SICK)
2. Millen Racing class 7s Fj
3. Team Necessary class 7s Fj
Millen and Necessary were on TV the show was called "Two Roads to Baja" great show recomend you watch it if you haven't.
Donahoe has some pictures of theres on here some were you can also see the buildup of the truck
here The guys from Donahoe are on here some times.
You should be fine with pulling the stock seats you just might get a light or two on the dash.