Personally i didnt scale the single mask at all from the kens file.. here is what its look like
Sorry for the crappy pics.. cellphone's picture.. and i know the mask is off a bit.. need lik ajustment.View attachment 342634
Its a budget faceshell modified from tjack
It seems it fits perfectly, I don't know what happened with mine, I didn't modify it but I can't even close the zipper, and my head is smallish, I'll have to scale it to 10% larger