Thanks for taking the time to do good pictures of your Loewe, I don't suppose the bands with unit marks have a matching serial (68) to the rifle? We have a little research thread trending these rifles and although it has a lot of moving parts (details being trended) it does give some idea of ranges and how common these are seen compared to other makers and dates. I also know of several dedicated collector-researchers that specialize in the G88, unfortunately most do not frequent this forum, but they have done good work on the subject and a few even communicated information to Storz project on the 88.
You might search them out, there use to be a forum called parallax or something like that and they use to have significant discussions. Of course you are welcome here too!