The 2L 4P is not a dead giveaway that it is an SS. That same designation applied to L30 327, M20 Saginaw 4 speed cars as well. I wouldn't throw this out as doubt except the horn button is 6 months too early for a July built car. The 350 was removed from the button in January, when the 396 was released. The OP would need to verify the location of the speedo cable thru the firewall to be more certain it's an SS with a Muncie trans. He, also, claims there are no numbers on the block... rebuilt and decked that early in it's life, or a 327 in hiding ? Missing the POP and the stamp ink blurred from moisture adds to the mystique.