Anyway you can post the pad stamp and vin stamp? And not in this section. Then, several thousand eyes can perhaps clarify those numbers. Someone with more experience will hopefully chime in. Because I feel that late of build car, if that vin is as you say on the block, it could be possible to have a July block?
Great the heads are a matched set. Those K dates. Are they 68 or 69? Either way, I don’t think those could have been correct for your car’s build date. One, too early, if 68. The other, 69, too late. Best of luck.