My Mustang 64-1/2-70 Restoration Guide (p. 335-Corcoran and Davis,1992) displays a pulley application chart that lists the correct pulley for a non-smog '67 390 to be p/n C5AZ-10344-K. The actual numbers stamped on that will be C5AF-10A352 (B, F, G, K, or L). There's also a C8AE number that gets stamped on later service replacement units. Here's an eBay auction of what looks to be an authentic original piece.
https://www.ebay.com/itm/NOS-1965-19...-/333583794998