Pickle where do you live?
Biggest OS I've found has been on Vancouver island. I haven't found anything very big on the mainland. As stated already it makes awesome arrows.
OS needs to very dry, or it will take brutal set.
It's very dense wood, and holds moisture deep.
I finished tillering an OS bow that was seasoned as a blank for almost a year and half. Maybe the stress of it being a bow played part but the handle checked wide open. I didn't even fill it in, as long as it goes down the centre of the handle it should be fine.
I've only made 3 OS bows, but plan to make a lot more (if this wood ever dries)
Here is one of them, close to the dimensions your dealing with, cheers
http://www.primitivearcher.com/smf/index.php?topic=50747.0