I got something mocked up,
Gives me an idea of the perfect frame dimensions, I saw a steel frame Trek when I went to the city, and looks as though it might work, at least now I have a definite ideal.
I tested the suspension travel on the rear, and with the cranks dropped 70mm from highest possible position, 320mm down to 250mm I got a bit over 40mm of spring compression, and so an effective rear suspension travel of around 6" with around 2" off spring compression.
This mock up has also given me a good idea of what top tube angle I'm looking for, as that will affect the rake, this Apollo frame had a fairly horizontal top frame which has messed with my rake. I hope I can find the right frame for it,
It appears to me the swing arm mount needs to be lifted relative to the motor by a little for perfect chain tension with rider weight, but it's pretty close.