Just a quick post, not sure I can help but many years ago I put a fiat tipe sedicvalvole engine into a kitcar and couldn't get it to run (complete injection ECU etc.) it turned out that the lambda sensor and crank sensor connections had the same plug on them and I had simply swapped them over by accident. Might be worth checking.
Also if my memory serves me correctly the crank sensor is a hall effect trigger and so when the engine spins it generates a small electrical current, if you put an LED test light across the disconnected sensor and spin the engine the LED should flash very quickly. It only works with an LED as the sensor doesn't generate enough current to light a normal bulb.
One more thing, a friend of mine had a fiat tipo that failed to start and it was a loose earth wire onto the ECU, might be worth putting a jump lead from the body to the ECU to make sure its earthed down.
Best of luck, these problems can be a nightmare but in my experience it usually turns out to be something simple.