I'm very familiar with these Zenith back when was big name with major institutions (started worked with computing dept in university from 1998 thru 1990's). Many of the zenith computers are perfect with DOS and win 3.x but they often don't have standard boards in them, except standard ISA slots (either 8 or 16 bits if they have that).
You will need zenith case with this correct backplane to start with. Voltages +5V -5V, +12V and -12V and plenty of grounds, nonstandard PSU plugs, in pinch, solder wires on the backplane to a PCAT style plugs pigtail if Zenith PSU is dead which is fairly common. Functionally-wise perfectly compatible with DOS, floppy drives standard interface, HD pick any and you can choose any hard drive controllers even SCSI. Memory is also Zenth card, for this one, you use DIP dram chips, always parity.
Their Zenith cases is NON-standard, black pointy tipped screws, and HEAVY in everything but slots openings for cards and PSU is also proprietary big way. Even inside PSU is so strangely designed with component that Zenith used house part numbers on the parts. Big bugger to troubleshoot when to fix. Only real cool thing about this is row of red LEDs for the voltage rails on the zenith designed backplane board.
You can leave out the video board and use standard ISA video card and multi i/o cards in place of this video board.
Use cmos setting program similar to PC/AT otherwise use zenith setup program for this.
Great Northern aka Canada.