We made a good progress on Zelenograd's PK32 (L1839VM1 CPU in particular). Given an info about this CPU is limited we were able to partially reproduce behavior using sources of DOS.
At the current state the 1839 is able to run simple user's VAX-11 code. Any advice/help is appreciated for further progress.
https://github.com/mamedev/mame/pull/13107