Rivets look original. If they are flush inside and rims hold air, they probably are.
The “B6 2x” are the date code, I believe. Not sure exactly how to interpret but likely Feb of 66.
The 1st set I had used 3 rivets/spoke and were plainly dated 1966 but these required trim rings and were more like Marauder rims...so maybe a slightly different production process.
I’m no expert but have owned 3 sets, all 15x6...so obviously not OEM 67 Shelby.
I sold 2 sets over time & RE-rimmed to 7”/kept the 3rd set.
Nobody here or in the US seemed very interested as they weren’t ‘real’ (& repos) but the guy in France (Ebay) was extremely happy to buy mine (only had 3 of) them for his 68 Mustang resto. Imagine how hard it is to find em in Europe. I’m SURE he’d buy your spare.
If the chrome condition is excellent, they’ll sell. The problem is, restoring them puts the price out of reach when Paradise & China make alternatives. If these were on a Carroll Shelby or a Larry Shinoda prototype or personal vehicle, that’d be a different story....
Good luck. If I had a 67/8 Shelby, I’d have em on my car as drivers...