As was observed for the 1966 highs, sometimes a high demand card like Perez is misidentified as an SP, even though it is not an SP.
Since the series has 77 cards, there is no doubt that there are SPs in this series. But as Cliff pointed out in an earlier post, reconstructing the 6th series sheet is just about impossible unless more miscut or uncut material pops up. Here are a couple of interesting cards I've seen.
1967_495.jpg
1967_shaw_wb_470_503.jpg