It's rough building the larger systems though. All the early logic is still around for the most part, but most of the "medium integration" parts have disappeared. Things like register files and bitslice ALUs. (74x181, etc.)
It’s not difficult to buy old 74x181 and 74x182 ICs on eBay. You can even get sixteen-bit ALUs like the IDT 7831 for decent prices.
Build a register file from a bank of registers. For example, use a 74x138 and a few 74x377.
Alternatively, either use a true dual port SRAM to build a three port register file, or build your own from a time-multiplexed SRAM and some bus transceivers.
Complex combinational logic can be implemented in an EEPROM truth table pretty easily.
Sometimes, part of the fun is figuring out how to build a complex device from a very limited palette of parts.
My favourite search engines failed to find that one (or I failed to look deep enough). Do you have a link?
There's also an additional project[2], but it seems stalled with no progress during the past few years.
1. https://github.com/pineapple-one/about
2. https://hackaday.com/2018/02/09/a-risc-v-that-the-rest-of-us...