I would sure do a lot of diagnostic work before going down the rebuild road. My gut reaction is you don’t need a rebuild. It was a sudden event. I suppose a piston or rings could crack suddenly but my bet is fuel pump or injection pump.
I think there was two of them. The last I knew the other Mustang had been found in Mexico in very bad shape. The one that sold for big money was sold as a used car and a women teacher drove it for several years.