I already looked at that, and as I dont own any jacket that fits like a leather should, and my other ones being intended for winter I went with this logic:
Gitman Bros shirt size M:
to me it looks quite close to ToJ 50, but I am not sure taking account for layering. What makes you think i would be swimming it a 50?
Measure your body, dude. And worst case scenario, if you have no jackets, go to a store, find a jacket that fits you and then take measurements from that. Charly should be able to guide you after your measurements are made.