The release dates are correct for the Pastels in TBM.
NW Buckeye has the paperwork for all three Century label pressings of Pastels 45s and he provided the dates back in the 1990s.
I've had both label versions of "What Can I Say?" (one with, one without the Century logo) and there was no discernible difference in the mixes, if there was I would have kept both 45s.