I have tested for spark only using grounded plug method. Nothing. I have good spark coming out of coil wire with a spark gap test off ground while grounding points wire. This tells me my switch box and coil are working correct? Now I'm looking towards the distributor as the problem. I'm pretty sure the timing hasn't been messed with since it was running a few years ago,(assuming that is correct). What's my next move before I take it to a professional?