I thought I would share one of my recent projects, the MCL65+, which is a drop-in 6502 CPU replacement board which can run either cycle accurate or in an accelerated mode. It uses a Teensy 4.1 microcontrtoller board which is similar to an Arduino, except much faster (600Mhz).
The MCL65+ PCB contains the Teensy and the required voltage-level buffers using through-hole logic to make it inexpensive and easy to produce.
I was able to use the MCL65+ successfully in a VIC-20 and an Apple II+. In both cases I was able to run a number of applications in both cycle accurate mode, and an accelertated mode which appears to be more than 10X faster than the original 1Mhz 6502!
All of the design files are open-sourced and on GitHub: GitHub Source Code Link
There are a number of picures and videos of the MCL65+ on my WordPress website: WordPress Blog Link
I have a number of spare PCB's available if anyone is interested in trying this out and experiencing the World's Fastest VIC-20 and Apple II+ machines! :) :)