Unfortunately since most trim pieces are unique to big B-body cars and chrome trim being used only in the high end models it limits the number of donor cars that can be used to find the parts you need.
The Impala SS, and the convertible share these trim pieces, and you might find similar parts on other GM cars of the era (though not all years used the same parts at the same time).
I have some pieces available. Send me a message if you are still looking for some. I am parting out 4 '60's although only 1 is an Impala 2-Dr HT, but I also have some other misc pieces available as well.
-Parting Out over 75 '58 to '73 Full Size Chevy Cars-
-National Impala Association
-Vintage Chevrolet Club of America