ajoe,
The engine must spin over adequately, have the proper supply of fuel and spark, and the mechanicals such as valve lash and timing must be within specs. If you have new ignition components, the timing is proper and the valves are set correctly, my bet would be on a carburetion glitch.
Do you have a choke? Does it start easier if you choke it? If your carburetor has a weak bladder, it might be flooding the engine. Before you start it, stomp the throttle to the floor and hold it for 60 seconds or so...don't let it up! With it still down, try to start the truck.
If it is a carb problem, it should start easier with the choke pulled partially out...OR, it should start easier doing the 'stomp the pedal' routine.
If these make no difference, verify all your tune up specs...point gap, timing, plug gap and valve lash. If you pull a plug wire while cranking the engine over (key ON), a spark should easily jump a 1/4" air gap to ground.
Make sure your exhaust system isn't mashed or plugged too. Good luck and keep us posted.
Stuart
