'65 Mustang Hi-po vs '65 Formula S

1966-7 back in South Ga. there was a college kid at Tifton that has "purpose" bult 289 Stang, 4 speed. He ran for $100 anywhere and anybody there was a country 1/4 mi. flat spot, and rarely lost.
He shifted by earand took the carhome every weekend for a "tune"> He swor it as stoke but we knew it had to be way more, maybe Carrol Shelby touched that engine maybe? He outran everything on a reguar basis.