Stilty-
That 1655 you linked to; me no likey
Case looks to be a bad replacement. Number of things wrong with it including the rehaut you mentioned (too small of diameter, too thick), the CG's and their shape, the lugs, the caseback. In addition, the bezel doesn't look like any that I've seen; it looks close to a Mk. 4, but certain details disqualify it from that distinction.
In general, this is one that just looks odd at first glance and even stranger once you start drilling down into the details of it.