Interesting idea on standardising on frequencies/channels for radio comms. I like the simplicity of the 321 idea.
Its American and group specific so the details are not 100% relevant for other countries/groups but for the UK it would be something like:
PMR446 CH3 446.05625MHz
UK FM CB Ch3 27.62125MHz
CEPT FM/SSB CB Ch3 26.985MHz
UK Business VHF high band Ch3 173.05MHz
UK Business UHF Ch3 449.475Mhz
Amateur bands are a bit different but that's why we have calling frequencies
Thoughts?