Dead in the Water...'67 Electrical Problem...

When you unplug the plug at location 14289 & 14401 on which side is the wire bad? Have you tried removing the wire from the coil and checking voltage with ignition switch on? The schematics look like power is coming from 16a and is pigtailed to 16b at the plug connection. There is a resistor showing after the switch. I would remove wire 16 at the coil and ohm it and check for a short. Also, check the coil and make sure it wasn't defective and shorted internally.

perhaps too little, too late but here goes .... have both 14290/14401 connectors been pulled apart? ... not clear from your first description .... wire #37A/37 is like the main buss wire to the fuse panel and ign switch and is one of the three wires of a flat connector ... if that connector has been separated, hard to see where the current is flowing from .... since the MSD 6A should have replaced all of the OEM coil wiring, wire #16 from coil to 14289/14401 flat three-wire connector should be non-functional .... if that were hanging around it may have shorted to something and caused this problem .... and it should be equally "smoked" .... wire #16A is a resistance wire ("pink") behind the dash that served as a ballast resistor for the OEM coil/points circuit -- this too is no longer needed but could provide a "run signal" circuit for the 6A .... would think that if you broke circuit #37A/37, the 16B wire smoking would cease .... then I'd look for a short from the firewall to the ign switch following wire #16B .... and check to ensure wire #16 (the battery side of coil in the old OEM setup) is not causing problems somehow as noted before .... since the MSD 6A is powered by separate wires tied directly to the battery, a shorted coil should impact those (new) wires I would guess ....

fwiw -- good luck !!

Check the terminal on the coil to the coil's case and see if the coil is shorted to the case. I had this problem about 30 years ago. In my case the car would run up to the point where it would keep smoking the ballast resistor I had installed.