Andy - how about AN4STT ?
I've never gone the Vanity route.... consider going for the Extra exam, and check the 'new call sign' box, and see what you get ?
That's what I did 30+ years ago....
Fred, KQ6Q
(was Advanced class, W7HSS before I checked the box!)
Not Valid. 2x3 calls cannot begin with A, only K or W.