I have a number of 1960s & 1970s TV series in my DVD collection. Although they are all in their original broadcast TV 4:3 aspect ratio, I've noticed particularly on those advertised as "Digitally Remastered", the image quality is quite impressive - to my eyes, anyway - when played on my BD player, and viewed on my HDTV.
I would call it near-HD quality. Certainly looks better that I ever remember those series looking when they were originally broadcast, and viewed on the typical TV sets of that era.
I have a number of shows from that era on DVD, and I have noticed the same thing, even though the DVDs that I have are at a native resolution of 480i. When I play them through the BluRay and HDMI cable onto the HDTV, they look much better than they ever have before. I would love to see these shows originally shot on film digitally remastered and recorded as a true BluRay in OAR.