I Need saddle advice?

For the bridle and rug there aren't a lot of choices. I'm guessing he would be standard horse size in those, most of the OTTB I've messed with are. I would opt for a wider saddle and more padding before getting something too narrow that will pinch. If you are at a barn with other people you may want to try other saddles on him to see what fits just right. Different brands run different too. Good luck.