What size helmet should I go for?

Hi there! I've been lingering around for a while, getting some ideas for a costume! Just wish I'd have found TDH before I started building. But then, I'd have found how involved it all is and probably have shyed away!! I'm 5' 10" tall of slim to medium build. What size should my bucket be? I foolishly bought a DP '97 as this project was supposed to be a quick, cheap fancy dress outfit for a party last November and suffice to say, Boba didn't make the party as he wasn't dressed - I'm still working on it - at my own speed now!
The DP '97 seems to be about the right size ratio to my frame but will need alot of work to get it accurate enough. I was thinking of starting a scratch build using WoFs templates - and there's the question - what percentage should I scale the pdf templates down to. I would understand his templates are the size of the original screen seen helmet and Jeremy was considerably taller than me I think!! Any help would be appreciated before I dive in head first again!! Cheers.

He is only 6'1" if i remember correctly so I would say two inches shorter should still use a full sized bucket.

Okay dokey! Thanks for that Dr3w. And am I right in thinking WoFs templates are sized accurately to the original helmet?

how do I size the bucket down for my 6 year old?