The 75MHz board should work as long as the board fits the cabinet. Based upon what you said, I do not believe you have the "control in a box" version. I do not know how much RAM it has, on board video, ISA slots, etc.
If the battery leaks it typically takes out the 12 VDC traces on the board so it becomes useless.
Everything should plug in. You will have to set the CMOS. Try machinemanuals.net for some manuals on your machine. Runs on DOS 6.20 so you will need those disks, if you hard drive is bad, and the machine software.