Fried Blue Fld wire from Alternator

Just of S&Gs. What's the resistance of the ohmmeter just touching the leads together?

It looks to me like they own you a new harness.
Good luck with that.

You had the bad luck of connecting the ignition wire to the grounded brush.
If you had connected the J2 wire to the insulated brush all that would have happened is overcharging and maybe burning some things out.

This is a constant problem with rebuilds these days.
Discussed in a few posts here: Identifying Chrysler Alternators (1960-1976)

And if that's a revised squareback, do yourself a favor and get something different.
if its a regular squareback, remove the brushes and measure the resistance between the slip rings.
If its in spec, buy some brush insulators and insulated washers and you can use it.