I posted this on another forum, where Mr. Strayhorn came back with a couple details I'd missed while looking at them in person!
1. The LG 52M, second from top on the left, also has double-set triggers (VERY rare. The DST unit on the early Walters is quite different from the one used on the LG 55 and LGV, too).
2. The LG 55, second from top on the right, has a one-off factory custom stock. It's ambidextrous, with cheekpieces on both sides. The original owner worked for Walther!