I think you should be fine. The only thing i can think of would be a bar behind the seats to hold the seat belts at the proper angle ( forgot what angle that should be) Also those belts might not be good after looking at them more they are what a 3 point and they dont have what they call and...
Did a bunch of stuff to the car past few months
Radiator ducting
relocated oil cooler
3g master cylinder
Rear adjustable upper, lower control arms
5 lug upgrade
4 bolt upgrade
evo max lock
17x9 w/ 255/40/17 NT-01's
! Awesome dude. I hope you get everything figured out. I just built ducting for my radiator and a bunch of other stuff. Hopefully ill get out to Fontana in Nov. I would love to meet up