1968 K-Code Heads - What is the deal?

I have a set of K-Code heads that are marked cast in 1968 - I am gathering they are either replacement heads or possibly from a early 68 or late 67 k-code engine?

The weird part is you can clearly see where the head should say '289' instead it appears to have had a '302' cast instead on the bottom. The 3 & 0 are ground off but you can still make out the '2'. Also I noticed that crane stamped their own numbers on them (to denote they are fireball ported heads) however the original casting code is ground off and stamped with a C8ZE instead.

They are definitely 289 K-Heads there is the cast in spring pockets, screw-in studs & the rest of the proper markings on them.

Does anyone have a clue what is the real story may be?

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I see through searching the forum they are indeed service replacement heads however I didn't realize that they could come from the factory with a 302 cast in them on the bottom and 289 cast on top.... interesting to say at the least!