I live to debark the whole log to see what is underneath, then decide where to split it. You could potentially get 4 bows out of that log, at least 2.
Generally I would suggest that, since you don't know about the back, and now the belly, to do some reading and/or get some OJT making your first bow, but assuming that is not an option I would tell you to draw a line down the crown of your stave with lines paralleling it just over an inch away on each side and cut on those lines so that you have a 2+" wide stave. Then cut down the belly so the thickness of the whole thing is about 2", from tip to tip.
So you'll end up with a 2+ x 2+ " stave, flat on the belly, following the crown on the sides. Take some pics of it and post it and ask more questions.