However, it is pretty much square-on (unlike the one on Landships) so you could use it as a basis for tracing it and be reasonably certain the proportions would be right.
Roger, thank you very much for your effort! However, I have already found those images...
The image I require would have to be far larger, and of exceptional photographic quality.
Ok... I'll let my little plan out of the bag...
Im going to aquire high quality images of the devil, and the Mephisto lettering, touch it up in photoshop, make everything a little clearer, smoothe out the nicks & scratches, etc, make it look real pretty (but using the same image), and put up a T-Shirt on Cafe-Press.
CafePress is a free online shop, that lets you submit images for them to print on T-Shirts, coffe mugs, mouse pads, etc.
I. Want. A. Mephisto. T-Shirt. I have wanted one for a long time, and by damn golly, I'm gonna make myself one - then we can all buy Mephisto T-Shirts online. Awesome eh?
However, for what you want to do, I think you'd be better off tracing anyway, in which case it doesn't matter (within reason, of course!) how poor the original image is, because it will only be a foundation. To have something T-shirt size would need a very large image, bitmap-wise, whereas a vector graphic (as would be a tracing) is a different kettle of fish entirely...
Mark Whitmore's book Mephisto - A7V Sturmpanzerwagen 506 - a History of the Sole Surviving First World War German Tank has a pretty good version of the image on it's frontispiece, if I recall correctly. Can't find it at the moment....