My first attempt at cleaning the fleece was mostly a disaster. The majority of the fleece felted so I was left with about 10% unfelted, clean fleece. I pulled off the surviving locks and am storing them in a plastic bag. Since I have no idea what kind of fleece this is or- really- what to do with it once it is clean I'm starting to research local resources for combing, carding and spinning.
The length of the locks is about 3.5 to 4 inches and, to my untrained abilities, feels fine and soft. So... not terrible for a free fleece. Lucky, I have two more fleeces for practice. I think I'll try the yarn harlot's method for cleaning fleece for the next batch.