More progress: The third memory card that was throwing errors on test #3 is now working again. What I did was pull the 82385 cache controller chip off the socket, then found that the pins were gunked with dust and junk. Cleaned the pins off with compressed air, put the chip back on, and now it's working.
So I have 3 memory boards now. The last thing to do is rebuild the power supplies and figure out why the last motherboard isn't doing anything. It's a complete dud, doesn't even turn off any of the LEDs on the back to start a test. I've pulled, tested, and re-seated all the big chips, maybe it's time to work on the smaller ones....
Also got the IP addresses changed, and updated the resolvers to point to my current domain master DNS server instead of using 30 year old cached BIND files. Turns out you just need to run the appropriate make (make hosts to update yp with the local copy of /etc/hosts for example) in /var/yp. So with that done Suntools is up, my old accounts are there, and the NCSA 1.0 web server from 1994 or so that I compiled is still there and working.
But man the system is slooooo compared to modern systems. That's ok, it does work. Wonder if I could patch sendmail, bind 4, sendmail 8, and build a ssh host strong enough to put it on the internet again......
Edit: Fired up Suntools and found the DOS image still has checkit and Lemmings! Man I haven't seen checkit in 30 years, it was a diagnostic/demo program that I used all the time and lost all the copies of. Fun to see it back.
Edit: Need to figure out how to set a modern date. Date command is useless, and although it will roll over to 2000 if set to 991231, setting a modern date throws it back to 1923...