I finally have it presentable. Now I'm ordering the hit to make it public, so I'll put the link here shortly.

- USB and PS2 keyboard, with USA, UK, SP and DE distributions
- Standard Atari 3-button joystick, all directions and buttons programmable to any key on the ZX81
Link to the repository with all informacion.
https://github.com/wilco2009/ZX81KBD-PLUS