For those playing at home, the hive-mind tally so far:
287 pages of content
+14 title pages
+ 5 covers
+12 JD 2012 Christmas story (which would be a brilliant addition, and up the Dredd content)
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318
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The book's 320 pages. That only leaves two pages for all the framework around it.
If the layout falls the right way, there is no need to intersperse the stories with those black pages they use to ensure the stories start on the correct page and any double page spreads or other cross-page shenanigans aren't back to back instead of side by side.
But even if that all fit together okay, then two pages wouldn't be enough. One page for contents. One page for copyright and address blather. But you still need a page with the writers and artists CVs, and they'll probably add an introduction explaining what Dice Man was and how it came about, etc.
It could fit if the covers were reproduced only as, say, small illustrations dotted around the intro, but I think it's more likely Christmas Dredd won't be included. As fitting as it is, it wasn't part of Dice Man.