340 Not firing on all cylinders

I did switch out a wire but I switched it both at the plug and at the distributor. If I swap it with another position on the distributor (putting it out of time) would I be able to properly tell if it is actually firing?
all I meant was change the entire wire with one that is firing to find out if the wire is broken / burnt or otherwise. sounds like you did that already. even better if you have a new wire you can put on the cylinder that isn't firing