The "brand" was "100+"mags...not a lot of info on them..but they were bought/absorbed years ago. Like you, no center caps...I'm guessing getting a diameter of the center and a good tire shop can figure something out. For some reason, I really like the look of these. Everyone has a fetish..). The set on my 69 I had laser lathe the surface after powdercoating black. Low maintaince and look purty..).
The rebuild looks like your making headway..Always admire people that can do the rust work.
Update of sorts... 100+ Made in England. 'Octavio'. Popular in early 70's sports cars, drove into oblivion apparently. ) Found this on a wheel site.. The car a 'Nostalgia Japanese Car' from the same years...