I just did this swap on my car, except I'm keeping the S14 ECU & wiring harness- I extended power wires from the ECU to a custom plug I made for my chassis. (definitely easier than swapping dizzy & intake btw!
Pull your coils, crank the engine, and check for voltage on your coils. If you're not getting any, then it's most likely the distributor. If you are getting some, then change the spark plugs.