One of the challenges was how do we get a good hold of these 6 x 6 posts at the center of the walls so we can pull them together? Nailed on metal straps or wood blocks won't withstand the forces involved.

Also, we are not dealing with minor loads and forces here. The come-along we are using is a 2 ton capable puller and the two yellow tow straps are rated for over a ton of force each. So we are able to put almost 4000 pounds of pressure on these posts. The way in which we connect to them needs to be able to handle that load with a safety margin.

We ran 5 loops of 3/8 steel cable behind the posts at each side of the barn. I bought a 50 foot package of cable, cut it in half and wrapped one 25 foot piece around each post and double clamped the ends together. 3/8 cable is good for 1000 pounds per stand so these 5 strands are enough to hold our load.

As you are setting this up for yourself, keep safety in mind, We purposely used these yellow tow straps instead of chains or cables not because they're cheaper. But, because we wanted something with some give or elasticity to it so it would keep tension on the building all of the time. But that elasticity comes at a price, if these straps come loose, because the cables or puller, etc failed, the straps are going to recoil so hard they will take out the side wall.. and ANYTHING in their path.