Interesting 1965 Formula S Info.

author calls them both pretty close and surmised with the same gear ratio and engine they would be real close Heck the Barracuda gave 36 hp and 32 ft/lbs to the "K" mustang. Give him a 275/273 with that tachless "S". He did say he lined up the Hottest version of each car you could buy from a dealer for the contest, tell them the 275/273 was dealer available.