Morning Maciej,
You could use simh /w 2.11BSD, or if you want to test it on real hardware I have a 11/83 where you could test?Then there is a fix for the PDP11 backend addressing an issue I found in the handling of floating-point comparisons. Unlike all the other changes this one has not been regression-tested, not even built as I have no idea how to prepare a development environment for a PDP11 target (also none of my VAX pieces is old enough to support PDP11 machine code execution).
-- R