Not a great deal of progress as I've been distracted by other projects.
Roll hoop as supplied needs work to replicate missing detail, it's a snug fit so no room for error. Where the back support meets the hoop there should be two brackets and a tube with a bolt through. Also the bar that carries the head rest should be mounted in a similar way, I didn't manage to capture this detail in any of my pictures.
I replaced a screw cap which fits behind the drivers head with one turned from alloy, it just looks more realistic I think.
Radiators and nose cone support structure added along with the bottom hoses with foil clips. The last picture shows what I believe to be a bottle that supplies air to the driver in case of fire. I removed the moulded fitting from the end and replaced it with telescopic alloy tubing. the retaining straps were made from alloy foil tape.
Thanks for looking.
7 attached images. Click to enlarge.