i think it looks ok, and in keeping with the style of the coat. i wouldn't try to tailor, any time i've done that the results have not been good.
(if any internet fashion experts call you out, just tell them it's CCP)
be warned, margiela coats often have a slightly odd cut. structured shoulder, emphatically waisted silhouette and long, sometimes slightly flared, skirt. it's not for everyone. would probably work best on a tall skinny dude though
both nice enough but garret is very thick and stiff, didn't fall particularly well (on me at least). OL lapels and fairly coarse fabric put me off. neither worth buying at retail for me, i'd consider on sale