Did you check the sizing thread? Actual dimensions are not as important as how the helmet fits your head. I would think youll need a DP 95/96 at minimum and possibly a 1:1.
The Hasbro Boba Fett (HBF) helmet that you see in stores now is 1:1 in scale. It takes ALOT of work and may not be the BEST choice but, if you have one or know someone with one or can sneak one on your head in a store for a pic we can tell you if that's the size you need to work with or smaller.
