You say where does the earth from the coil go to?
The positive side of the coil goes to the ignition switch.
The negative side goes to the ignition amplifier module. What used to be the points.
The rev counter is also on the negative side of the coil.
It is important to get the coil the right way round as there is an internal ballast on the positive side, inside the coil.
The suppressor /condenser is often a problem (if fitted) as they don't make them like they used to.
Run the earth wire from the distributer to a good earth or back to the battery if its in the engine bay.
I had electronic ignition on my old car and had problems getting a good suppressor, it would work on the points system but not with the electronic system. I tried three or four before I got one to work.
Good luck.
Pete.
There must be a Powerspark wiring diagram on the internet. That would help.