C8 means 1968, Z means Mustang and E means engine. The 9425A seems to indicate a cast-iron 4-barrel manifold from a J-code 302 (230 HP).

Unless I have missed something, I think it should fit a 260 / 289.

Like most of the late ’60’s Mustang stuff, it is not worth much from a performance standpoint, but might be worth a fair amount to someone doing a proper restoration.