[rdorman]

Modern seats would go a long way. If you don't want that a number of the original racers had a THICKLY padded 'head rest' bolted to the roll bar. Fuel cell I think is a must so is some sort of collision shut off for electric fuel pumps. I have seen a number of vintage pictures of Cobras racing with a full width forward braced roll bar so while they may not be the norm, much less all that attractive, there is a historical president. Of course, a fire system is always a nice idea.
Rick