From my own experience... there are two (EDIT: US) versions of this poster.
1. Studio Issue -- It only has the NSS number in the lower right. I have full size (27"x41") bootleg that I got suckered into purchasing, but I don't have an original to do a proper comparison. The reason I know it is a bootleg is because Todd at MPGrading tested the paper and there is no alkaline in it. Movie poster paper stock didn't come without alkaline until the mid 80s so this poster was printed after this time. The paper stock also appears to have come from Japan (based on the presence of different pulps). This paper stock matches bootlegs for The Thing (also full length 41") and Pulp Fiction (regular) that Todd has also tested. Presumably that means these bootlegs were all printed at the same time in the mid-90s or later.
2. NSS Issue -- It has the NSS number in the lower right, but it also has the name in block print and an NSS paragraph just right of center at the bottom. This is a deceiving poster as the fine print text in that NSS paragraph is fuzzy -- which would normally lead you to believe that this is a bootleg. However, my full-sized (27"x41") rolled copy perfectly matches folded NSS versions and it was also authenticated by MPGrading. There was a discussion of this version on MOPO a while back and the consensus was that it is indeed original despite the fuzzy paragraph. I'm not sure if there are full size bootlegs of this version, but I would guess not. This style rarely shows up rolled... if there were boots you would think it would be more common.
Best of luck. If I were doing it again I would hold out for the NSS version. By the way, if anyone has a guaranteed original, folded studio issue -- I'd be happy to send over my rolled bootleg for a comparison. Maybe we can then figure out the tell-tale signs on how to avoid them. The text looks a bit fuzzy on mine, but so does my NSS so I don't think you can go by that exclusively.