Not absolutely certain on a 52 but more than likely the same as my 59. This area was originally covered with a jute backed firewall cover constructed of oil impregnated cardboard. Don't think you will have any luck locating a repro though. I ended up going with the ABS plastic and am totally satisfied so far. You will find others made of fiberglass but I don't recommend the rubber ones offered by some suppliers as they are cheap, cheap, cheap.
