It may inspire others, however; and even if it's not a different processor (I'd love to see a Z80 version) there's still plenty of room to shrink this one and yet remain discrete --- looking at https://cdn.evilmadscientist.com/sites/6502/images/A1_4.jpg you can see there are huge areas of empty space between the transistors and LEDs, and that package is not as small as SMD transistors come. Halving each dimension (1/4 the area) should be possible in a revised design, reducing PCB costs and making it more palm-sized. Alternatively, the same size of board can hold 4x the transistors, meaning a Z80 would fit comfortably.

Is there a way to set the processor's clock? It'd be nice if the user could slow it down make it easier to observe and understand the state changes. Maybe even support breaking execution in order to read the state.

A Z80 or 68k would be way cool!

You can do that with http://visual6502.org/ today! :)

Let’s face it. The circuit board is covered in Blinky lights and runs 6502 code. What’s not to like?