Barrel length has nothing to do with accuracy. If anything shorter theoretically means more accurate. You will lose a little velocity, but cutting it off an inch or so is really your best alternative.
It can't hurt to try yourself, if you don't like the results you get you could always pay a pro to re-cut it. It does need a new crown. It might be cheaper to pay a gunsmith rather than pay for a tool you'll likely only use once. This is a job almost any gunsmith should be able to do. Surely he isn't worse than a DIY project by someone who has never done any gunsmithing.