I see 200rpm when cranking in the efi dashboard, but my conventional tach, hooked to the msd tach output, is completely dead, no bouncing at all.

This is telling me the dizzy is ok and either msd or ecu have trouble I think.

Is the next step to substitute the msd box? I grabbed another used 6a box from the shop last weekend. Is there a way to test the white trigger wire my ecu is sending pulses to the msd on? (the points trigger wire)