Well, even though the Dubya isn't a real MC powerhouse, it should still out-accellerate 95%+ of the cars on the road, and hit 85 mph and more with no trouble, eventually pop you over the "ton." If it will do that, or close, it probably doesn't have a blown head gasket!
You might try to clean up the stains with solvent or something, and then watch them to see if they reappear. It could be a mess left over from the PO, like the oily airbox and air filters.
Like Jon Haddock said (he's got an opinion on everything . . !!), if it's not exhibiting other symtoms, just ride it!
Old . . . and . . . Slow