Backfiring out exhaust

It DOES NOT MATTER here where the drive gear is.
When you reinstall the distributor, you will have to retime the distributor and the wires and then you are right back where you started, having solved nothing.
You could have solved the proble much easier by just rotating the the distributor to the next lode on the cam, and rewiring the cap to match.

Hoewever, the starting point is to always verify the marks on your balancer are correct. If the ring has slipped , then you gotta fix that problem first. To that end, prove that TDC/compression on #1 cylinder is synchronized to TDC on the Balancer. Then check your timing-chain slack. Typically 2 to 4 degrees will be fine. By the time you get to 10 degrees, your cam is late to the party, and so is your ignition timing. The timing you can put back, but the cam is still late. The cam drives the Distributor gear, which opens the points. You can retime the Distributor to idle, but when you rev it up it may not fire to the right tower.
So figure that out. Your timing light should/might tell you about that spark scatter, but defeat the VA first.
If you have electronic ignition then just substitute the word "pole-piece" for points.

Your coil specs are close enough.