Is it possible for the stock computer to only control the fuel and not ignition so I could still use the lt4 intake and have a distributor in the back?

 

You could run the ignition off a distributor, with its own centrifugal and vacuum advance. You would still need the optical sensor in the Opti to feed the cam position to the stock PCM. It needs the low res pulse to fire the injectors in the correct sequence. It will not run without the low res pulse.