I'd guess that the early one came off of a Falcon, with the 144, or 170, instead of the 200. Even some of the early Mustangs came with a 170. So, I'm guessing that the early one may not flow as much as the later one. I'd go with the C8.
"Get your facts straight first, then you can distort them as much as you wish"!!
1965 Fastback, Sunlit Gold, I6, T-5, Pertronix, CAA AC, SSBC frt discs