This project is a small daughterboard adapter that replaces a 6502 processor (used in vintage 8-bit computers such as the VIC-20 and BBC Micro) with a modern, currently manufactured CMOS equivalent, plus a bus transceiver and some passives.
Two versions of the daughterboard are available (long and short), which fit different motherboards. At the time of publication of this post, the adapter had been successfully tested in Commodore VIC-20 computers (in both versions of the VIC-20's motherboard) and an Apple ][+.
For more information, PCB Gerber files and full documentation, please check out the project's repository on Github.