I was having a look on the official Woodstock site and the only version they have on this is the Johannesburg edition,, the only difference i can see and it maybe just the photo,but the white background appears to be alot duller than the official one they have online... my two cents worth.
I also have doubts about the projectionist background story, yes, back then projectionists used to change the posters on a Thursday night but in no way did cinemas receive 100`s of these now or back then. Imagine the numbers involved of sending out 100 odd posters at a time to any cinema of the era,there was simply no need on either side.
The poster you have posted looks to be trimmed on both sides,,the Quotation marks on either side of the title should have a bigger margin.
Take a gamble Mel if you like too,but dont pay over the odds if you can avoid doing so.
(sorry Mel i just noticed you had already bought)
Stew