Instead of guessing about the position of the distributor you need to determine what's really going on. Take off your valve cover and crank the motor by hand (it'll go easier if you take out your spark plugs) and watch the number four cyl (closest to the firewall) rocker arms--when they get to the point that one is closing as the other is opening, stop rotating the motor. Your motor is now on the firing stroke of the number 1 cylinder. Now rotate the motor just enough to line up the timing marks. Now observe which way the rotor points--that's #1. It may or may not be pointing where it should because the drive gear could have been installed incorrectly. If it's wrong, now would be a good time to set it right but in the interest of seeing it run you can just make that #1 and install the wires in the cap accordingly. Now do a rough timing--you can use a test light or piece of thin paper. Loosen the clamp on the distributor and rotate the body counterclockwise so the timing will be radically late--the points are closed. Set the test light from ground to the distributor side of the coil terminal--or pry open the points gently and slip the piece of paper between the contacts. If your using the test light you need to turn the ignition on at this point. With the points closed the test light should be off. Slowly rotate the body of the distributor clockwise so the point will open. When the test light goes on--or the paper can slip out between the points you can shut the ignition and tighten the distributor clamp. Your timing will be within a degree or two of being perfect. Certainly close enough that you can eliminate timing as a problem. Be sure you don't leave paper between the contacts. If your still getting backfires and no start think about the movement of the rocker arms---are there any that barely move? Think cam and lifters. Good Luck