Wiper condition today after 50 years has allot to do with what we we and find on these cars. Left alone many can show the affects of the elements on the finish while cleaning and polishing can create differences in the other direction
Here are some examples from all the same time period at San Jose in 66 (6R130000-about 136000)
And from later in the year
6R163xxx
6R178xxx
6R186xxx
6R196xxx
6R2042xx
Personally for the vast majority of the production year (later period of the two) I would focus to find something that looks like the example 6R196xxx above. Happens to belong to a car I've know since the 80's very nice unrestored car that spent most if its life (after the initial years) stored inside under covers but not polished and detailed. Don't think its ever been buffed.