Haven't gotten a new power supply yet, or finished upgrading one by myself, however I did put the VOC and PC Transporter and SCSI card back into the machine, thus occupying all 7 slots as well as the memory slot (with planning and careful management of card protrusions to prevent shorts, this is possible). With the TransWarp GS at just 7MHz and the new low-power components installed on that board, the machine will run with all 7 cards inserted and the case lid on, indefinitely. Those TWGS upgrades help so much even if you don't swap crystals.
(For the interested, that's 1:Uthernet 2:PCTransporter 3:TransWarpGS 4:MicroDrive Turbo 5:VOC 6:MDIDeas SuperSonic 7:SCSI MM:GS Sauce 4MB. I'll get pictures soon.)
Also, I'd like to tell you that the 8x2 internal joystick pin header shouldn't be used due to logistical inconvenience as well as the idea that a good yank would stress your 20-year-old logic board. But none of those reasons applied to me, I just snipped that pin header off of my Kraft joystick (same model pictured above) when I got tired of trying to argue it through the GS back ports. A few weeks later, I picked up the wreckage, identified the wires in the cord, and put a nice Radio Shack DB9 metal plug on it and screwed it to the back of the GS. It works wonderfully, and my countless games of Task Force and Xenocide are testament to that fact.
Oh, and the Uthernet card is working great. I was able to configure it and use the textmode telnet program that comes with Marinetti. I've yet to more fully explore it, but now that I've got a joystick and a pretty stable system, I've got a million things I wanna try when I get time.
There aren't many hardware improvements and tinkerings left to do at this point, so I promise I'll get back to programming.
-Chris