​hmm - no idea.  I don't remember having had such problems to be honest.  Maybe we can find the a tp image.   I'm sure they reason they used a tar image was, that tp was  more problematic​.

That said, I still think the tar image should work.   Maybe the solution is try to compiler stp with a modern C compiler.  It will take some work to move it I suspect because the code would be 100% assuming PDP-11 in every way, and is binary.  Plus things like stat.h are a bit different than in the old days.   Let's take this off-line and let see what's possible.