For fun I've attached a disk image which sets up the CPCs screen size to the equivalent of the following systems:
* Sega Megadrive
* MSX1
* Sega Master System
* Nintendo NES
* Atari ST
* C64
* Sega Game Gear
* ZX Spectrum
It uses mode 1 and sets the pixel resolution. There is no attempt to match the actual aspect ratio and pixel sizes as that can't be done on the CPC.
I'll post the source along with other source soon.
Make VGA maybe someone will make a custom monitor for the emulator. ACE-DL is the closest.