You can plainly see this was a Lord Baltimore Press production. Also quite prominent are the color keys and some alignment crosses at left, center and right (The crosses are also visible at the bottom).
I'll blow up the entire left side waste area above the cards and below the key to make the discussion easier:
I often talk about blocks of cards on a press sheet being arrayed in an ABA/BAB pattern across the two slits when an 88 card series was being printed. Each letter represent the same 44 card block on the slits, but the Board "A" reference is merely coincidental here (I think) as Topps also would prepare and proof their art work in batches of 44 (or 55, 22 or even 33), depending upon the configuration of the series being printed. I assume this is because each slit had at least one batch on it and they could move around the films shot by the printer or each accordingly. You can see the proof date, or at least the month (March) and what I assume is a batch order number (6-803) or some other such reference. It's not clear to me if that's a Topps notation or one from LBP but I suspect the latter.
The cards on the A Board run from nos. 201 to 285, entirely consistent with a 110 card first series, followed by two series of 88 cards each. It's a little weird that Carl Erskine's name does not appear on the proof. I know he voluntarily retired on June 15, 1959 so the printing predated that but occurred during spring training. Perhaps he was contemplating retirement before the start of the season and caused Topps some pause? Or it's just a goof-up. Here's the finished card:
Board B would have had the other 44 cards from the series, including Fence Busters (with Ed Mathews and Hank Aaron), Early Wynn, a couple of team cards, a second year Maris and some not-so-hot rookie cards. Kind of a meh series overall, talent-wise, isn't it? In fact the whole set only has a couple of big name cards but it's a release that I've always liked the looks of thanks to the big blocks of color and well-designed backs.
So a neat little bit of Topps printing history there-too bad there's no complete record but of course, what else would those of us who dig this stuff do if there was?