Fitted the seats and seats belt today.
I used the original inertia seat belts still in the original position and just re-routed the top seat belt runner.
The lower fixings are through a 30x4 flat bar bolted through the floor and the 50x25x4 box section floor support
Also fitted a pair of fiberglass seats which enabled me to see how the seat belts functioned.
The bonnet is presenting a few problems so I re-enforced it to stop it flexing so much.
The whole thing coming together nicely so I think I am ready to permanently bond/bolt the body to the chassis.