I've found some skinny Keystone wheels, and held on to them, hoping to get a decent rear set I can use. Turns out, if you have the burden of knowing the difference between original ones, vs the current- new offerings... We'll they aren't as easy to come by as you would hope.
I with my early Chevelle, and my sister's Nova- a 15x8 is all they can take. So I bought some flaking 15x10 and had they cut apart, restored and used a new barrel to create a 15x8 with 5.25" offset.
So far, I am happy with the results.