I don't k now where what wires have been snipped. Joining the J2 & J3 is fine with an MSD, although not neccessary.
My diagram is just a rework of the circuits of interest based on the factory diagram.
According to the diagram
The ignition feed went to a welded splice. I don't know if that's how it actually was done in production.
The feed is supposed to be a 16 ga wire with blue insulation and a white stripe.
The branches are either 16 ga or 18 ga and do not have the stripe.
IF this diagram is accurate, then there were two blue wires at the ballast resistor.
J2A brought power to the ballast resistor,
J2B joined J2A at the connector.
^This^ type of daisy chaining was done as much as possible in production. It minimized welded splices, and I assume saved money and made it easier to wrap and route harnesses.
Example from an original '67 harness
If your car was originally equiped with electronic ignition there's some slight differences but the concept is the same.
Here's the ballast resistor wiring on a supposed '72 survivor at 2019 carlisle
The J2 here must have its branch to the voltage regulator begin elsewhere - probbaly a welded splice.
The green wire here is actually green with red strip and used to help control current to the ECU.
