If you are sure there is no short in any of the wires or ignition switch or plug wire or plug...those are easy to examine and relitively cheap to replace....then I suspect a bad coil.

Scott


edit-

If it misses consistantly....you know it's going to miss....then I would hold a test light on the positive side of the coil....if light does not flicker when it misses then there is nothing wrong with the power supply (wires, switch) and it has to be points or coil or plug or plug wire.