Hey,
I'm assuming 4 lug? If that's the case there your choices will be limited,as 64-66 6 cylinders left the factory with 4 lug steel rims and hubcaps. There are not alot of aftermarket offerings that will bolt up.
If you're bringing it back to stock,you're most of the way there the car appears to have some of the optional wirewheel spinner hubcaps.
One thing to consider I've always been very leary of the stock 64-66 6 cylinder spindles ,they were light duty. If you place wide rims /tires on them it places extra stress on them. I've seen a bunch break over the years.Scary stuff.
I have a feeling your car is/was a "Sprint" Model. I 'd be curious what your air cleaner looks like? What is your cars build date? Does or did you car have a center console? Do you happen to know if the quarters were ever replaced? Just curious.