Cranks but won't start?

Did the car ever run when you had the 6 in it? Are you sure the engine is timed correctly for inital start up on TDC on compression stroke? Any spark at all? It sounds like it may be wiring related. Make sure the wiring to the distributor is in good shape. It could also be a pick up problem but I would definatly put a new ballest resistor on it to be sure.