Making progress...
The system had been fully disassembled & PSU checked (and oddly enough appears to be in mint condition). New hardware is standing by, this is going to be an interesting build!
I've decided to pair this one with Mitsumi drives (both floppy & CD-ROM), but I have no idea what I'm going to do with gaping 3.5" hole in front, as it seems to be too small for one of those 3.5" fillers which I got laying around.
Took the liberty of removing the motherboard, and adding (and replacing) the mounting standoffs. While the motherboard tray was removed, I also used the opportunity to mount (and screw in) all the drives. Oddly enough, this PSU requires external ground, which I connected to floppy... I really don't see the point for additional ground terminal, but whatever... Also, the live voltage cable is now routed around the frame & looped down into the switch. Rather than having a live cable dangling inside the case, and near low voltage areas, which could be sensitive to EM radiation from the mains (220V, 50Hz)
The sound card for this build is going to be ESS AudioDrive MS868P/D. The last time I had it hooked up, it kept causing weird problems & other issues, so I'm going to give it one more (and probably last) chance. If this one doesn't work out, I'm going to swap it out for SoundBlaster 16, which has a non-working MIDI. Which would under the normal circumstances be a serious issue, but since this particular build is going to feature Win95 & 1996 (and newer) software, I don't see any problems.
Oh, and almost forgot... Can't go without the CMOS speaker!
Fortunately, I had one, laying around.
And there you have it... Still tons of work to be done, but I'm slowly getting there!