Slot Mag Question

I'm doing a "Day 2" build on my '75 Duster and need some thoughts/advice on current wheel direction. I have a pair of 15X8 aluminum slot mags (uni-lug with inserts) that I would like to use in the back. I haven't found a manufacturer stamped on the rims. They are mechanically in great shape, but very oxidized. I don't have a matching front set and would like to run a 15x4.5" or 5" rim. I can't seem to find any used skinny slots, that are not ridiculously overpriced. My only other option is the US Indy Mag (U101) 15x5", which is highly polished. Is it possible to get the same highly polished look on my old 15x8's, or am I going to have two different finished wheels if I attempt to use old and new?