Can the gas tank heat shield be removed if the exhaust headers are not installed and the rear deck lid has been removed?
Sure can. The aluminum brackets holding the stock three-layer heat shield on my '72 L were pop-riveted to the frame. Either drill the rivet heads off, or use a pry bar to shear the rivets, then remove the shield and grind off the remainder. The stock assembly can be polished but the shiny-ness won't last long. When you return it, both the tank and shield can be repositioned an inch or so, for more clearance and mounted with sheet metal screws for 'next time'.