Funny thing is that the car that's pictured is actually a 1967 model ( look at its grille , bumper , and flat hood ) .
Perhaps it's the first GSS Dart ; a Slant Six-powered GT that received a 383 / 727 / 8.75" with 3.55's from a 1966 Coronet and under chassis headers ( highly unusual for that time ; total custom job ! ) . That's the one that was featured in -- iirc -- Car Craft's Feb '67 issue .
As a side note : I e-mailed Norm Kraus himself to inquire about the first GSS , mentioning how I read the Car Craft article ; he denied the whole conversion !!
Wish I still had access to that issue ( a friend has it , and he lives 2,000 miles away ... )
just so that I could confirm that I did indeed see that article .