has reached (almost) it's conclusion. Seat installed, tested and approved by various anklebiters, 3 belts now on it so almost sorted. There are 2 things I'd still like to do, one is to find a way of retaining the seat cushion and 2 is to reinforce the floor a bit. The disco rear floor is sufficiently thin and flexible that the seat ain't quite as rigid as I'd hoped.
Photos to follow when I get tuits to upload the ones I've taken already of the frame and to take some more of the finished installation.