My understanding is Hurricane (who I wouldn't bother trying to contact - bit of a mess) did mods to his Kaiyodo facemask recast to make it more accurate.
Eczamurai, what dome are you going to use? Hurricane's Hasbro domes always looked a bit too big for the Kaiyodo facemask but maybe the Sideshow V2 helmet (slightly smaller than the Hasbro) might work.
Vaders always have to be viewed in low contrast, diffuse lighting to judge proportions and accuracy. High contrast seems to hide many inaccuracies (Sideshow Vader looks pretty good in high contrast.)
Jeez, you're going to be at $300+ (and countless hours of work) on getting this Sideshow Vader right... why didn't you wait for the HT Vader pics, then proceed if the HT has missed the mark?