a fuel fire will burn every thing no mater what .usually caused by a back fire or just a fuel leak .check all fuel hoses and clamps .replace any dried or rotted hoses.
this new fuel will melt regular rubber hose so i would replace it with fuel injection hose.
i still have a scar on the palm of my hand from my first mustang when the dash wiring caught fire and i reached in and pulled the wires out , it was a 66.