Wow, what a great project idea. Really slick how you added the PS2 controller connector too. Nicely done on that. This gives me an idea.
I have a couple of Commodore 64 cases lying around whose motherboards are in disrepair. I also happen to have a C64 -> USB keyboard adapter. I was originally going to use it to house a Raspberry Pi. But now I'm considering using it for a Basic Engine (I bought enough components to build 5).
Or... hold on. Could I use it to house both? There's plenty of room in there without the motherboard. Perhaps I could add a switch to toggle between which board the keyboard is connected to.
My only problem (as seen in another thread) is that I can't get firmware to upload to the BasicEngine. But that did lead me to build another board, so I already have an extra to throw into the C64 case.
Shameless addendum: I uhh... also would be grateful for any help getting my firmware uploaded. I'm not sure how active this board is these days so I'm excited to see someone who got their BasicEngine working who may be able to give me a pointer or two.