Hopefully someone on here will have some extra rims that you can acquire. You may also want to put a want ad in the Generator & Distributor.
There are some used rims for sale on eBay, but for the money they are asking, you may be better off buying reproduction rims. I purchased five 21" split rims from
Vintage Rims Australia. In bare steel, they were $910 shipped to Ohio. They're quality rims and I've been very happy with them. You can see some pictures here:
https://vccachat.org/ubbthreads.php...uperior-series-k-touring.html#Post444606Universal Vintage Tires also offers rims, but they do not have rim locks attached. You would have to weld them on yourself.