I'm sure you already know this, but it bears saying anyway - be incredibly careful about cleanup. Anything that will remove oxidation and tarnish will most likely happily remove the gold plate.
I'd consult with Black Beauty/ancient Ludwig guys, who are used to dealing with finishes and plating itching to fall off a drum at a moment's notice and an unkind glance, rendering it just another grubby old shell/lug/clip.
It would be worth you notifying Steve Maxwell of this beauty (not to sell to him!) but he has the scope on all the other Caddy Green kits in the world today. I think with your recent find, that would make it around 15?
Normally we have "LOOK AG THIS MIJ SET I SCORED FOR 100 BUCKS AT A YARD SALE" with a back story and a bunch of pics. Here we have a super rare historical significant set that has just been uncovered and we barely get pics and a few words. PLEASE WE NEED MORE!! PLEASE!