...I own three 5" barreled 27-2s, two of which are pristine, in the presentation case and in the same SN range as Bill's 5"er. I have no photos of them yet, but I committed to Bill that I will try and take and post a few during the next week or so.
Finally got the camera out and making good on my commitment to Bill. Here are the two - pretty close to matching 5"ers.
N361983 - shipped in August 1976:



...and N361912, also shipped in August 1976:



I bought them as a set, and my guess is that they were purchased by the original owner as a set...