leather will stretch...all the gears don't fit right...just like a leather shoes (specially dress shoes...)
if you start tailoring it...70~85% you will not be happy...they turnout like...oh well, will be end up in the closet rest of its life...I bought, joe rocket super moto pants, and its too big, (I'm 36 and they sent 36...) so I start asking around?...BOOM!!! no one will even touch that...long story short...tailors, have a regular sawing machine...they do have a technique but no equipment...shoe repair shop the other way around...
so, I learned from mistake...when it comes to the clothing, either go to local shop to try it on the store...to make sure its fit or, if you don't like that then try to find what brands fit you best and go on line, and order the right one for you...
to fixing the exsiting problem? go to shoe repair shop about the leather stretch spray...some shop will have it...but, chest 44 automatically comes in 36 waist...so, you should get, 2 piece suit...(Jacket, 54/Euro, 44/us, is a same thing...Pants, 30~32 should be Small but you have to check with stores... I hope this helped little...