Thanks Jack for the help. I only have your e-book because the physical copies are sold out. I certainly don't want to say that you are wrong because you are more of an expert than I. However I would like corroboration. I believe whether the sight glass is at the top or bottom is significant.
For example, if this pump were a version of the 70, then the only difference would be a cutout in the door for ad glass. If this were a version of the 577-R, then in order for Wayne to move the sight glass to the top, they would have had to change:
The sight glass cutout in the door
The Manifold mounting brackets
The light manifold
The cutout in the side for a higher hose exit hole.
So technologically and parts wise, this pump is closer to a 70 than a 577-R.
What would be nice to find is original literature identifying and showing a wayne pump with no ad glass and a high mounted sight glass. OR someone who has this pump with an attached original nameplate.
Maybe this research will help your book, but either way I'll be buying a copy.