That is fascinating Arwyn.
Those David Rutherford 4/4s were very rapid even with relatively low power engines due to the much lighter weight (thinner gauge steel chassis , one piece fibreglass tub, glass fibre wings etc.
I do remember the Chris Cooke car quite well . I think it had an all steel Martin(?) engine , a rocket box , and an Atlas rear axle . Very very quick , but not always 100% reliable. It was always trailored to the meetings at a time when many of us drove.
I was never a fan of the Pinto engine , although I know it can be well tuned, a bit too heavy for me liking.