A great project, allowed me to experiment more easily than with the real machine.
My SuSE Linux 10.2 requires -lrt to build with real time so I had to make a slight change to SIMHs makefile:
add LDFLAGS = -lrt inside "Unix environments"
Other than that it works fine with VMS 5.5-2. Ethernet works OK, I have installed UCX for TCP/IP and I can use my MacBook as an X-Terminal with it. :) Screenshot
The instructions here were also very useful.
SIMH has the capability to detect IDLE state in the emulated machine, so this line:
set cpu idle=VMS
added to vax.ini should keep the host system load reasonable.