So many excellent ideas here. Personally the bigger the better for me. Since this is such a milestone in not only exploitation and film generally but now UK censorship a celebration is in order!
Steelbook would be excellent as would a huge box like
Battle Royale's, perhaps with a soundtrack and t-shirt as has been mentioned.
Or perhaps a box shaped like a turtle in which you have to rip it open to get all the goodness inside. Ooh or maybe a Cannibal Holocaust cookbook!