That asbestos sheet may have had aluminum bonded to it. Some of the 40's -50's light fixtures (think drum-shape here) had this so the lamps would not radiate the heat up into the canopy, where house wiring is rated for only 60 C degrees. There is nothing under that chassis that heats up enough anyway.

I seriously doubt you need heat shielding, so you can remove it. A carefully-cut sheet of thin steel, slightly larger than than the chassis footprint is an option to provide shielding, which you also may not even need..

Progress update:
Ok, removed the asbestos that was stapled to the bottom of the cabinet after spraying it down with water.Removed what was left of the dial lens after removing the bezel.(interesting how it was "stapled" in)sprayed down what was left of the wasp's nests.(made a nice mud puddle at the bottom of the cabinet:D) After drying, i took a little elmer's glue to the tube layout sticker to stop from falling apart any further.Basically the only thing to do is to apply a little lemon oil to the interior and it's done till i get/make new parts for it...:yes:
Man, i hope the EPA doesn't go snooping though my garbage can....:para::D