Your posted image is way off on the dimensions, but you could offer him an 8x10, an 8x12 or an 11x14 at an OK quality and tell him that any larger will be not-so-good. If he insists, have him sign off on a not-sso-good image.
For that shot, yes, you can get the long dimension longer by stretching the canvas and cloning in Photoshop -- give it a try, and see if the effort is worth it, since you still will sacrifice print quality.
And now, this is a stab in the dark -- is this a "CD copy" of a shot taken by a hired wedding photog? If so, they often deliver a set of photos that can give decent prints at, say, 8x10, but to go larger is barking up the wrong tree, quality-wise.
And, if it's not your photo you should post a link, not the actual photo, unless the photog has released copy right privelidges to you!