Well, I pre-ordered at Zavvi because of the free delivery and I don't THINK they have a weight limit. I have purchased the Vanquish Figure Edition from them before which is pretty big, and when they do not ship internationally they usually note it in the item description as they do for the
Deus Ex Edition.
I live in Canada and am not 100% sure Zavvi won't send you an e-mail shortly before release that they cannot ship it to you, and I'm not 100% sure it will arrive in good shape (I have only used Zavvi in the past 6 months and have had no issues at all, but others have). But I can say....you're
probably safe pre-ordering from Zavvi. Haha, it would probably be safer getting someone to forward it to you but also more costly especially considering Zavvi has free delivery worldwide.
You could also try contacting Zavvi now about the edition's ability to be shipped to the US.