Word is he is no longer selling Cat stuff, but I was just able buy a new reproduction set for my PL 20 from George Logue at a reasonable price. It may have been his last set. You can try to reach 85 yr old George through www.logueind.com
Also, be aware there were two different hinge configuratiuons for Cat 20 louvered side curtains.
The hold down fasteners are still available from Cat dealers. Part number is T-537. The price for the 4 I bought last week was $44.37 each. I'm close to finishing the restoration of my PL 20.