One of the first parts in technical papers is a survey of existing works. 

Z8000 board (the Trump Card) by Steve Ciarcia in Byte magazine

Hardware: A full-length ISA board as a slave to the PC. Most of it is a massive array of sixty-four 4164 DRAM chips giving 512K of RAM. These could be replaced by a pair of 512K SRAM chips. Communication is through a 2K RAM with counter supplying the address lines.

Software: It ran a BASIC interpreter but I can't find it in any form on the web.

Documentation: Several articles in Byte magazine. 

Z8000 board by Rolf-Dieter Klein

Hardware: I believe this is documented in one of his books, but I can't find a copy online.

Software: There is a listing of a Z8000 BASIC interpreter (and the Z80 BASIC it was based on) in his book. I've had a go converting the listing into a form that can be assembled by non-Z8000 assemblers, but I have nothing to test it on yet.

Documentation: His books are in the German language. 

Z8000 board by Christopher Ramage

Hardware: He has made a PCB for this. An Atmel Arduino board is used for boot-up and debugging.

Software: Not publicly available.

Documentation: Just the circuit diagram.

Z8000 S8000 system by Zilog

Hardware: Lots of documentation on this website but the S8000 system is very big and used lots of small-scale TTL and chips of the period. So it is bigger and more complicated than necessary these days. 

Software: Many EPROM images with source code.

Documentation: Plenty. Some of the scanned circuit diagrams have been redrawn on a modern ECAD package, and are much easier to read.

Z8000 board videos by 737MHz

Hardware: Constructed on prototyping board.

Software: Runs BASIC. 

The videos show the board running BASIC but there is no verbal or written commentary.

Documentation:  No links to any documentation. 

The PC downloading software has a Japanese user interface, so searching for Japanese web-pages is a rich source of links.

Z8000 projects on Github

tgtakaoka has done a lot of work writing assemblers, and supporting the Z8000.

4sun5bu has a Z8001 project built on prototyping board with circuit diagrams and software. It boots from a microcontroller, and runs CP/M-8000. It is the most advanced project I can find.

4sun5bu is also this chap: https://www.blogger.com/profile/10308244904742468931 whose Japanese name translates to 4 inch 5 minutes. I think it refers to a size of dagger. His  blog  https://choisaki.blogspot.com/ has a lot of Z8000 stuff.

Scott M. Baker's Z8000 + CP/M 8000 project

Based on 4sun5bu's project, and laid out on PCBs. The memory is on a different card to the CPU.