A special thanks I owe to Old hillbilly's post which helped guide my choice of size:
https://indygear.net/cow/viewtopic.php?t=74985
My older jackets were size 46. If not for Old hillbilly's post, I would have gotten a size 42 or size 44, not having the courage to get a nonreturnable jacket that does not fit...
So I spent a lot of time measuring myself, measuring my old jackets, checking the measurements on Wested's site and comparing all to the post above and I took the plunge on the OTR Raiders Goat in size 40 and an OTR ToD Lamb in 42. I was very apprehensive that none would fit right, but I had a huge surprise when I got them. The Raiders is a perfect fit and the ToD is only ever so slightly too large, but a size 40 would most likely not fit me. I can wear a T-shirt and a thickish shirt beneath the jacket very comfortably. Just tried it out with an additional hoodie and it still works well with both jackets.
I am so happy since for the last months I had been sporting jackets where the shoulders reached halfway down my arms and the sleeves halfway down my fingers.

And here are some pics of the jackets. Raiders:




So, in the hopes I help someone else choose the right sized jacket I give my stats as well: I am 5 foot 8, 72 kg (158 pounds), chest circumference just above 42 (107-109 cm) inches.
Cheers,
Bear