@Mizmazzle Thx man for the detailed answer !
In the meantime I had contacted IH Germany, and indeed the charts measurements would have been ideal for me, but Axel was kind enough to measure the 2 "L" they have in stock, and P2P was 60,5cm (23,8189 inches), as for the only "M" it was 58,5cm (23,0315 inches) which is way to big for me sadly 
Real bummer since I had really been drooling at all the pictures you did post here on this thread; always wanted a very light brown leather jacket (all brown jacket are mostly too dark for my taste). Had also being eyeing IHSB-TGN-NAT, but the last "M" that would have fitted me is also sold 
Not sure I'm going to like the new leather from the pictures I saw but never say never 
I guess this is fate, I will stash the money away in the hope that something from the coming fall/winter collection blows my mind, which let's be honest, is very likely to happen 