I have decided to try and mock-up a prototype/POC I had a good search around I was certain to have some ATTiny's to prototype with and hopefully write some code that will be pin compatible with the final design.

In the end managed to settle on some through hole ATTiny85's .

Opened up AVR studio and raced to get it to blink. Did it:

It blink and on PB0 which is the pin i want to use for the main LED.

now just have to start figuring out how the states will work for sending the blink to other boards.