Marc, what an awesome, stripped-down, go-fast machine! It appears to be Burnished Brown or a sort of a flattened black, is it?
I grew up near Hamilton in Ancaster but have lived in Toronto since the mid-80s. I do remember a Frost Green '69 Biscayne in Ancaster circa 1975 that was a 427 car and was rolling on 5-spoke Appliance Mags. Repainted generic apple green in '76, I assumed that the Frost Green 427 Biscayne I saw a picture of in Brantford was the same car. It isn't, as the Brantford car still has original paint and the Carter Chevrolet emblem on the trunk
Circa 1980 I also saw a black '69 427 Biscayne at Trinity Road between Ancaster & Lynden at a body shop & also incorrectly assumed it might have been that same Frost Green Biscayne first seen around '75 (but it wasn't the same car).
Marc, you are in Burlington, correct? I remember at least 3 different big block '66 Biscayne posties for sale in Burlington around 1980, all with 4-speeds & Corvette Rally Wheels.