1971 Dart Detonation Issue

Good afternoon. I wanted to kick this issue out to the field of more experienced folks than I. My Dart has had the following and running for over 2 years:
1. MSD 6AL Box
2. MSD Blaster Coil
3. MSD Distributor (8534 Billet HEI Mag trigger Mechanical Advance)
4. 318 engine

I recently rebuilt by steering column and some suspension and header improvements. I initially had an issue where I only had power on the Yellow ignition switch and the starter would crank but no spark. I have resolved that issue, and it ended up being the new Ebay switch was defective.

Now I swapped it and she fires up! However, she is backfiring and popping. After a few pops it will shut off, and the battery is to weak to re-crank. If I put it on the charger, it will fire back up after a minute of juice.

When I did the headers I put new plugs in and I am Pretty SURE I put the plug wires back the same order. I know for a fact that I did on the driver's side. The passenger side MAY not. I used masking tape and just numbers each from 1-8. not by fire order but by cylinder front to back. So, the passenger side is either front to back 5,6,7,8 or back to front 5,6,7,8. I tried both ways and no difference.... which also seems odd.

The only other change was that I was told that with my set up, I can go from 6V to 12v to MSD 6AL, by connecting he wires on the left of the ballast to the thin red wire off MSD. I did this, and thought that was the issue. Like I said, I had been running the 6v Ballast set up for over 2 years fine. I tried again both ways. With the Ballast connected and without. Still backfires the same.
To be equal, I just realized that I need to try with ballast and the other possible plug order on passenger side and see if that helps.