Welcome to the forum.
The part number you referenced, C8ZE-9524-A, is for the intake manifold, not the engine. The manifold is a 4 barrel carburetor type used on the 1968 302CID V-8 only. The "K" is most likely a foundry reference that the exact meaning is lost in time. The engine casting number itself is located on the lower right rear of the block above the starter which you will need to remove to see. It should read C8OE-6015-A. There should be a casting date code there also, (year, month, day - examples 7L21, or 8B5) and an engine assembly date on a casting tab near the distributor, the same format as the casting. See the picture. There is a strong possibility that a partial VIN will be stamped on the left rear of the block.