Fried Blue Fld wire from Alternator

Assuming its the correct pulley and rotor, simplest route is to buy a new brush insulator and insulating washers.
or if the parts store selected the alternator for you, then you could have them get you a correct one. Whatever is easier for you.

Blue wires.
Look at how they are connect for '73.
Follow the wire segments back from the alternator field terminal that was grounded. Go all the way to the key switch if neccessary. With any luck the segment from the welded splice to the alternator was smaller gage than the wires further back.

edit

So start with wire J2 F at the alternator connection and work back to connector CE37.
That might be the Engine harness connector.
Then from that to the welded splice. Hopefully the J2C going back to the bulkhead connector is not damged because its 16 gage. I would check at the bulkhead connector too. Remove the terminal from cavity N and check it out visually.

Then pop its mate out and go under the dash and check it out.
And finally to be sure. check the J2 wire terminals in the column connector.