Mine was a bit later than that, but around 1982 I built a CP/M system using a Z-80 compatible HD64180. BYTE ran some articles back then (Chaos Manor) but I could not afford the boards. So I designed my own on breadboard (10x16cm experimenters PCB) with an Elektor 64-pin A/C backplane bus. I added 256KB RAM (The HD64180 had some crude bank switching mechanism), and later on build a floppy disk controller. Later on I added a separate Z-80 based video card and keyboard controller, and to top it off a SASI (no typo, Shugard Associates Systems Interface, not SCSI) controller. That attached to an Adaptec ACB4070 SASIRLL controller and a 10MB harddisk. Needed to partition it, as CP/M couldn't go beyond 8MB
I wrote my own BIOS for it, and implemented ZCPR-2. Looking back I just can't imagine how I ever found the time.
Feel free to play on my lawn ;-)