Hmmmm. You're kinda far long in the process so not sure how helpful my suggestion would be, but as much as they are good designs in their own right - they all seem a little...um...."sissy" for lack of a better word to me? (for this application I'm saying) I mean, when I think of tattoo shop I think something a little more raw, a little less refined maybe...grittier and more aggressive.
These all seem really slick and clean which may be appropriate depending on the type of tattoos he does...but the work of Art Chantry kind of comes to mind to me as inspiration on this. Might be worth a look. Good luck!