w1mx.mit.edu used to be a microvax-I. It ran ultrix, and later I'm
pretty sure it ran 4.2bsd (it was running the "project athena"
environment) but I know there were problems with the small amount of
memory (ultrix didn't run well in 4M either) It *might* have run 4.3,
though I know there were problems in later years with not having
enough of the missing instructions emulated for some software to
actually work. If you're up to expanding the emulator support, I'd
certainly give it a try (or at least try it and report here how far
you got. There's at least a chance of it working, as opposed to, say,
if you had a z80 or pdp-11 (you'd need UZI or bsd-2.11 respectively :-)