I'm no Ford guy but remember reading some info on these a couple years back when researching some Canadian Shell Endurance Rally stuff and I was searching for the Tour deFrance winning Mustang that actually ended up in Canada and disappeared..
Again I'm no Ford guy and I may be mixing up some of the Rally prepared car stuff I read but do recall the '64 Comets were being argued but ended up proven as definately built and had unique rears and ratios, distributors and underhood bracing also horsepower like 270...the big-car brakes were the rally cars only I think?.
I'll search and try and find what I read?.
Snce you have a build sheet, doesn't it show exactly what was shipped?.
~ Pete