In my experience, car geeks always want the rare stuff, no matter what the cost is. I know someone who imported some wheels from the Netherlands at a hefty cost. I think they were Fisher wheels, but don't quote me on that. All I know is that they were made a billion years ago and in a very limited quantity.
Sell them IMO, there will be someone who wants to be different and will pay to do so. Various tuners always build show cars for magazines and stuff, I wouldn't be surprised if they were interested in them. How many times have you seen a car in a mag, that has a description about some super obscure (therefore cool) part?
So yea, if I were you, I'd sell them. Wheels do break, bend, scratch and get stolen and I wouldn't want to deal with trying to find a replacement. Save the time and money and buy something that fits the standard hubs. Do the rear disc brake anyway, cause it's the right thing to do.
