While the concerns expressed by T. in Oklahoma and M.Ted are valid, I think they're overstated somewhat. I think it would be a stretch for anyone to take you to task for playing/recording "The Wreck of the Edmund Fitzgerald" more sensitively, and with different instrumentation (losing the heavy percussion and electric guitars, etc.). I don't believe that "changing the basic melody or fundamental character" would be read that broadly by most people, and I'll bet there's case law that puts boundaries on the interpretation of those terms, subjective though it may be. It's pretty common for people to record alternate arrangements of pop tunes without getting any flack for it. Would your rearrangement of "Edmund Fitzgerald" really be more radical than, say, a Muzak version of "Satisfaction"?