I would use a diode plug tester, think you might be able to use a small low voltage bulb. Just short it out across the terminals to check to see if a signals getting to the injector.
How did you test the injector?
Or if the heads off already check the condition of the cylinder bores, any petrol in the oil? Could also fill the cylinders with wd40 and leave overnight to check the rings are sealing.
Whats the condition of the head gasket, why has it blown? Could be quite an important clue.
Inlet valve on cylinder 1 ok and serviceable?
As much info as you can.
Whip
