MSD/Starting/Charging Issue, Novice Needs Help

Unless there is something IN THE CAR mis wired, or something wrong in your ign switch, the brown should be "dead" in run, so you should be able to tie together the brown/ blue to solve the start issue.

HERE IS WHY. Originally, many Mopars "kill" the blue line when you twist the key to start, and the power is replaced by the brown IN START ONLY. This brown went directly to the coil, so you got a nice hot spark, but when you RELEASE the key to run, the brown goes dead, the blue becomes hot, and the blue then feeds power THROUGH the ballast resistor to run the system.

You MAY be having a serious voltage drop issue IN THE CAR WIRING.

Turn the key to run, engine off, and measure the dark blue at some point, such as alternator field. You can measure voltage drop DIRECTLY by putting one probe directly on the battery positive, the other on the blue field connection. You should show LESS than 1/2 volt, and 1/2 volt is generous. MORE indicates a drop in the harness path ---from battery--fuse link--through bulkhead--ammeter circuit--to ignition switch connector--through switch and back out connector--back out bulkhead--to dark blue such as field.

No1 suspect is the bulkhead connector.