When people say they have a big head it's relative until you post measurements/size. What size hat do you wear? I feel I have a large head - I wear XL, or 7 3/4+ hats. I have a fully padded MLC v3 helmet and it fits perfectly.
Flak vest - Chef makes them. I also believe Niki Powers may make them - https://www.facebook.com/dreams2seamscostumes
Regarding Cucblack (Christian) - I just received my jumpsuit and flak vest today. Both fit great. Christian is a good guy in my opinion.