I took a chance when acquiring the suit as the jacket was closer to a size 40; while I am a regular size 37. But the lovely fabric - a heavy Cheviot in Dark Olive with warm orange/red overchecks - and the fact that the trousers fits perfectly convinced me that I would overcome the needed fitting of the jacket.
For a while I have been considering to do some alterations of a jacket myself as I would like to try making a perfect fit; I gained some sartorial experience and interest when I a few years ago made some Medieval 14th century clothing (jackets, hoses, trousers, waist coats and hats) entirely by hand.
So this weekend's experiment is driven by pure curiosity and endeavour to splendor; more than trying to avoid my alterations tailor and his fee. Even though such costs would equal a lovely new Stenström's shirt...
I detached both sleeves as the jacket needed to be narrowed in shoulders, chest and shortened in sleeve lenght.
Then I narrowed the shoulders by 1"1/4 each; I also removed excess fabric under the arms narrowing the chest and cutting the armholes higher.
Next step is to attach the sleeves; at the same time making sure that the sleeve lenght will be perfect.