The Z8 interface to RC2014 is not too complicated. The bus is demultiplexed with a 74HC573. Half of  a 74HC139 turns the DS and RW signals into Z80 style \RD and \WR. The other half of it uses DM (data memory), A15 and a GPIO pin so that memory is accessed except when data request for > 0x8000 occur and the GPIO line is low in which case IORQ is lowered instead. This allows a program to programmatically map 32K of I/O space. Possibly it would be better to ignore A15 and just require the user switches mappings for external data access and gets the full 64K. I may change that for a second revision.

A 74HC00 completes the logic providing an inverter for the IRQ input, one to generate MREQ and IORQ and a third inverter for AS to latch the 74HC573 correctly. I used a 74HC00 because I have some to hand, it's also nicer to have  a spare NAND gate rather than inverters on a board  for any debugging problems.

For a crystal you need something that gives sane baud rates if you want to use internal I/O. I am currently using a 7.3728MHz standard RC2014 crystal and 19200 baud but double that would work.

It should be possible to use this board with the ROM BASIC Z8671. I've not tried it with any of the older parts. In that case you need the RAM jumpered low and ROM high, and to burn the designed baud rate setting into ROM.