Why would you want a tattoo of a word in a language that you don't understand, written by someone else who doesn't understand it, on the basis of a stranger's recommendation on the internet? That just doesn't make sense to me.... So, I don't know what you should use...
i was wondering about that meself. i meant as you aged, things get sagged and could change the characters. from a slant stroke to a vertical stroke, and the meaning could change from "good luck" to "stupid gaijin".