Somewhere I have some images shot with an Orestor 135/2.8 that I borrowed while still at school around 1970. I used the lens on my Zenit E and it was extremely sharp.
Meyer optics were used by both Pentacon (Praktika M42 screw) and also on Exactas in bayonet mount. Both manufacturers offered a line up of budget Meyer optics or the more expensive and wider range of Carl Ziess Jena lenses.
Most of the Meyer M42 lenses were very reasonable performers, the exception being the 50mm f2.8 Domiplan.