Here are the mounts for the outboard front seat
Here is the inboard front seat belt
The rear seat belts are designed to attach right to the seat frame and there
is no provision for should
The outboard rear seat belt is only 17" long because it attaches to the seat
There is no adjustment on the outboard rear seat belt.
The inboard rear seat belt is 30" long fully extended and can be adjusted as tight as you want it:
I don't particularly like the idea of the rear seat belts being attached to the seat. Seems like all your eggs are in one basket and if the seat lets go, you are strapped to it but you have an ejection seat thing going on.