Do you have a cage or roll bar in your car? Otherwise, the 4-point harness is useless to you. Also, in some states and provinces, they aren't legal for a street driven vehicle.
I'm using the black belt set out of an 86 Dodge van in my 72 Demon. The reel & cover take a big chunk out of the rear seat foot room. Otherwise, I'm pleased. It's a big improvement over the originals