Hi, thanks. :)
I think that using blockly to handle ZX Spectrum code could be a good idea. I was thinking to do that with NES code (or Vic20 or C64 - I am only expert on 6502 assembly, I have just a minimum knowledge of z80 assembly) after I am done with this project for Atari 2600 (but I believe that this project will take a long time to stabilize).