Here's some of my Soviet/Eastern European regs.
This is a Soviet AVM-3, which is a second stage regulator. It's supposed to be a part of a package which includes two tanks, a remote first stage, piping, SPG, etc. I have it cobbled up with all kinds of adapters to test it. I thought a qc would be the way to go, but it is too long. However, it appears to be a great candidate for chest mounting:
IMG_3069 by Vancetp, on Flickr
IMG_2964 by Vancetp, on Flickr
Here's the system (which I do not have!):
s-l1600 (3) by Vancetp, on Flickr
This is an AVM-1M, which is a two stage regulator. According to the Soviet Manual of Scuba Diving, the AVM-3 was an improved version of the AVM-1M because it provided a point for surface air to be pumped to the diver:
AVM-1M3 by Vancetp, on Flickr
AVM-1M6 by Vancetp, on Flickr
The Soviet hoseloops sometimes did not utilize non-return valves, so I found a set of WWs from a Sportsways mouthpiece that fit well:
IMG_3039 by Vancetp, on Flickr
And this is a Polish Kaiman single stage regulator. This one came with non-return valves. The hoses, mouthpiece and duckbill are retained by fine mono-filament:
IMG_3240 by Vancetp, on Flickr
IMG_3247 by Vancetp, on Flickr
IMG_3245 by Vancetp, on Flickr
IMG_3238 by Vancetp, on Flickr
The Soviet regs are kind of crude, but are pretty good breathers. Odd that they used squid for duckbills!