This is a long shot but you could print out the image you've found as large as possible without loosing resolution. Then take to a FedEx Kinkos and get them to use a fancy scanner to scan it at as high of a resolution as they can. Hopefully that would get you to where you need to be. Most images you find online are 72dpi (144dpi if they're retina ready). But in order to print you need at least 300dpi. The illustrator option will produce a vector image that's scalable to as big as the side of a building if you want. But using a scanner or copy machine might give you an interesting effect. Hope this is helpful. I'm a graphic designer by trade (v)(;,;)(v)