OK, now we're getting someplace! <smile> The description as I read it, is that the starter does not operate when you turn the key, but if you jump across the starter terminals it operates.... if I have it wrong, please feel free to correct me.
If this is the case, then there is probably no power getting to the small terminal on the starter solenoid from the relay.
Here is a wiring schematic of the system to help you:
As you can see, power passes from the ignition switch, to the neutral safety switch, to the relay, which then closes and applies power to the starter solenoid. The most likely point of failure, since you have replaced everything else, is the neutral safety switch on the transmission. I would suggest taking a test light and following the wiring, to see where the power in the circuit is being lost... that will be the location of the fault.
Neutral switch operation and location appears to be different depending on whether you have the 3 speed or 4 speed transmission; both were available in that model.