In my opinion, a selfbow MIGHT be possible. But that thing's got some issues.
Following the grain is an important consideration, and since it was sawed across the grain, not hand split WITH the grain, you may have issues there. It doesn't appear to be a clear piece, so I'm guessing the grain is doing some funky stuff.
By looking at the picture, there are other concerns as well... by looking at the end of the board, the outer growth rings appear to be leaning, i.e. not perpendicular to the sawed sides. If you were dead set on making a selfbow with it, I would stand that big board up in a vice, and remove the sapwood with a drawknife and scraper down to a single heartwood ring. Then you'd have a better idea of how the curvature of the potential selfbow's back ran, and you could see the grain in the newly revealed growth ring to know if a selfbow was even still possible. If not, I'd probably seek the clearest section long enough for 36-40" quartersawn slats, and then splice them together and back them with hickory or bamboo.
But to be honest, that board looks kind of rough. I don't know if there is enough good clean wood in there for slats either. There appear to be several big knots in there, and is that a big crack in the middle of the board or a saw mark? I gotta keep telling myself it is 7.5' long and that there's a lot of wood there... but I just don't know. Can you take pictures of the bottom, right side, and close-ups of the ends?
What is the history of this piece? How was it dried, stored, cared for?