You mentioned an extrenal coil? Are you using some sort of aftermarket ignition system? If so, make sure everything is wired correctly for that so your getting power. I woud have the battery checked, but it doesn't sound like that's the problem. If your getting fuel, all you need is spark and the correct timing. Make sure you check that too. turn the engine to TDC on the crank pulley and make sure the cam gears also line up as being set to TDC. Also, if the distributor is set all the way retarded or advanced, try changing that back around the middle and see if that helps (if the spark is too late or too early, it might not start). Aside from that, you've got just start eliminating the posibilities. Seeya.