The exposure looks good to me. I think I would have gone with f/5.6 instead of f/2.8 (in the landscape composition). That way, the bottom of the post, the lower right part of the rear spur, and the buckle on top would be in focus. Of the two orientations, I think the landscape one is better. In the portrait one, the gray mass in the lower left corner is distracting and there's more of the out-of-focus post.
Good choice of the post. It has a lot of character and deftly symbolizes age and weathering.
I do have one suggestion for the landscape version. I'm not one to slavishly adhere to the rule of thirds. However, in this case, since it's a memorial piece, I think moving the subject to the left would leave room for inserting text on the right, perhaps with the father-in-law's name and birth and death year. Just a thought. A mounted and framed print would be a nice holiday gift for your friend.