+1 Frank, sorry to hear of Your loss, too. Just noticed that topic.
Last friday I was in local MOT-office (single purpose companys here; not garages of similar, just for MOT) and kept serious lesson to officers about dangers of roll cage in road car.
Underlined there must be 4-6 point belts with cage, and enough tolerance between head and tubes.
Foam padding when hard enough is ok, but when using a car in under FIA-rule competiton (like all my rallyings), then You must have FIA-type foam paddings. And that material is almost as hard as rock. When installing to my car (it, I hitted one narrow extra piece of it with 1 kg / 2,2 lbs hammer. Looks like black stryrox, but it didn`t crack, and there wasn`t any signs of hit... So I think it`s not good for Your skull, it`s ok only when using a helmet.