A quick update:
The bulk of the 7400 chips showed up: 7400, 7408, 7432, and 74139. I was also able to verify the capacitor position for the 40-pin connector (e.g. for the Z80 CPU and the Mega1284 PIO controller). I'm still waiting on the 28-pin sockets to verify those.
On the firmware front, I wrote a library for parsing and encoding Intel Hex files; it's a simpler format that I think I'd prefer to use for writing the EEPROM in AEPRO. It also has the capability of doing FNV-1a hashes to verify data. I laid out a quick MCP I/O expander test board; it uses the MC23017 because code that works for the low ports will also work with the MCP23008. I expect I'll be ordering that alongside the other boards once I validate the 28-pin connector. I'm also working on laying out a 7-segment address and data display.