Your car must of had fuel all along, because it will not backfire without fuel and fire both.
There has to be a problem in the timing as you have mentioned. The first thing to check is the cap and rotor. If the cap is cracked you will see a line inside the cap going from one plug wire pin to another, or to the center coil pin. The rotor can have a hole burnt through it but this normaly don't cause a backfire. If there is a hole in the rotor it will look like a small dot inside where the shaft goes, that is as small as the point of a pin. If you change the dist cap either number your wires, or put the new cap in place and move one wire at a time.
Does the starter sound normal or is maybe spinning a little faster than normal? You might have a timing chain out, so we need to be sure it is in time. Here is how to;
(1) Remove #1 sparkplug. (Drivers side front)
(2) Have someone bump the starter a little at a time until compression comes out the plug hole. (hold your finger over the plug hole)
(3) When compression comes out you will need to turn the engine just a little more to line the timing marks up on the front balancer to right on zero. (There will be a timing marker down on the front pulley)
(4) With the engine on TDC follow the plug wire from the plug removed to the dist cap and mark the dist. Now remove the dist cap and the rotor should be pointing directly to where #1 wire is on the cap, if it is not there is a problem.
There are other things like bad gas that can cause problems but here are some things to check.
Have fun, Larry www.lnjstreetrods.com