HELP NEEDED Identifying Brake Spindle - likely from a late 70s Volare

Those appear to be FMJ spindles, although it's hard to tell from the little bitty pictures. They may also be 73-76 A body spindles as they're almost identical, but the castings on those appear to be the later FMJ spindles.

There's nothing "cobbled together" or "mystifying" about that swap, it's VERY common to upgrade to the later disk brakes which also gives the more popular 5x4.5" bolt pattern.

The problem is the 14" wheels, as there are some styles of the 14" wheels that do not clear the later calipers. Most 14" wheels do, but there are a few reproductions that do not.

All of of the Wilwood conversions that would fit under a 14" wheel would be less braking power than the single piston calipers you already have, Wilwood is just expensive crap to say you've got it, many of their kits are inferior in stopping power compared to the later Mopar calipers.

That aside, pretty much all the Wilwood kits are for drum spindles, the majority of which use the small ball joint UCA, which you likely do not have, unless there's a ball joint spacer in there that can't be seen in the pictures. Because those spindles are for a large ball joint. I will also add that not all the Wilwood kits will clear ALL 14" wheels, so, you might very well end up with the same issue anyway.

I'm not sure where you're getting advice, but anyone that said to go to 14" wheels probably shouldn't be listened to. You have the brake set up and bolt pattern that most people spend a lot of money to upgrade to, ditch the crappy 14" wheels and call it good.