Full disclosure: as it happens, I have a 1st print up for sale on eBay this week.  It's been sitting on my shelf since I bought it locally years ago, and it appears to me it was never played with, poor thing.  On closer inspection, while it has what we currently have listed as a 1st print rulebook, it also has a 2nd print X1, and a 2nd print box bottom (red-bordered box, no product number in the lower right), but I have little doubt it was either a normal late-first variant or a "factory frankenstein" if you prefer.  This sort of thing occurred quite frequently.

I always find new printing information interesting, fantastic, and in need of further investigation particularly of the contents and possible differences between.  In addition to the listed variants on many rulebooks there are many variants, some of which Acaeum has catalogued better than others and it's always cool to add to that growing body of information.  That said, I think *most* people don't care about individual printings, let alone variants thereof.  It may be a bit premature to call one variant the True first, but time and more corroboration and investigation of the contents will bear that out either way, if people are willing/able to investigate.  I can't help any further on this one.

To my mind, if it's got the 1st printing rulebook, and it came from the factory that way, it's a first printing variant of some sort. It seems like the main feature, unless you're truly fascinated by the variants.  It also seems quite weird to me that the bottom box sequence would be: black-border without product code, black border with product code, then the 2nd red border without product code...but stranger things have happened.  Best of luck!