Chris, here's a couple of gates I built years ago. Had to replace some rotten boards on the garden gate today. As you can see I used gate guy wires with turn buckles. You must with a wooden gate or it will sag. Sorry to say but whoever built your gates shouldn't build gates. I would build new ones. Even with wheels those gates will never close together parallel. A steel or aluminum frame and the gate is stable forever. You can use the existing posts they're fine. The top right hinge has been moved down because of the split in the post but an extra long hinge bent in the vise to wrap around the back of the post will work fine.