What kind of decal are we talking about? Flames? I think most shops that do vinyl wraps should be able to make whatever you want. I had a custom racing stripe made for a bike a few years back, they adapted the design, printed it, cut it, and installed it, no sweat.
here's the place that did mine some 12-13 years ago. not sure where you're located, but they're in north carolina. if nothing else, some of the key words they use can help you find something comparable