Here is a link to a prior discussion on these:
http://www.net54baseball.com/showthr...ps+High+Number
I have to check but don't believe the 6th series was subject to "checklist lagging" a method where Topps would have checklists showing Series that were either 11 or 22 cards less than what was being printed on each sheet (long story) allowing them to preview some cards from the purported next series to keep the kiddies buying. '67 seems to be the first year they abandoned that practice since commencing it in the late 50's and it led to some funkiness after series 5 as some guides show the 6th series as having triple prints; not sure that's right but it indicates something was up. Don't forget though that the semi-high 6th series is more abundant today than the true highs. Some 67 high numbers are quite hard to track down.
No matter what, every image of a 67 high number half sheet is always of the same half.