what voltage should I have at the coil

Check and still no spark and still had only 3 and a half volts across the coil even with the jumper connected to the + battery post.

Ummmm, are you checking the voltage across the coil by putting the voltmeter leads directly on both coil terminals? You need to check for the recommended voltages with the voltmeter - lead to engine ground (And you can then check to chassis ground, then battery - if you like; this will make sure you have good grounds throughout.)

It is sounding like the distributor is not triggering the ECU, since you changed the coil and ECU (which we presume are good; are they known good spare parts?). Have you checked the wires from the distributor to the ECU thoroughly to make sure nothing is open or grounded? Look for odd kinks or really 'floppy' spots in these wires, indicating that the wire is broken on the inside of the insulation.

Or, maybe the ECU is not getting good power. Make sure you have 12V to pin 1 of the ECU connector with the ignition 'on', and check each ECU connecor pin for not being corroded or any broken/suspect wires.

Where does your spark tester hook up to? From the "HT" lead?

HT= high tension which is British for high voltage, and is the lead from the coil to the distributor cap.

And when you say your VM has 200 and 750 settings, is this AC volts?