(This is from the guy with a 35” chest and 38” arms)
You might be able to get lucky and fit into something in a 38L, however, I doubt the sleeves on any jacket that needs to be as slim as you’d require would work.
I’d take a look at a place like Indochino. I’d sign up for their email list and be on the hunt for any deals they might run. A blazer starts at $299. I realize that’s not cheap, but I’m fairly certain your sizing will be next to impossible to find unless you go MTM.
ADDING wienerswingtips said:
With measurements like those this guy should get checked for Marfan syndrome. No joke. Especially if he’s a young guy. Off topic, but it’s related to my field of work.
Uh, wow. Yeah, definitely worth looking into.