If you've seen a type 1 photo covered with whiteout and pen lines you've seen a newspapers original art.
Most original art is nicer than that, we worked from originals of many types. Usually text arranged electronically, with photos pasted on. Or old fashioned drawn art depending on the customer.
In the 80's color separations were done by photographing the original through both the halftone screen and a colored filter. (Or just the filter for stuff that printed solid like many of the topps frames)
T206s may have been halftones taken from the horner etc photos with the rest painted on celluloid sheets.
The celluloids would have been converted to monochrome negatives and those used to make what were basically like iron ons which were used to layout the individual images on the stone. The little side and top center marks are remnants of the alignment marks during layout.
I think the largest single color image we did while I was there was a book cover for Navy recruiting. One image of a plane from above, which filled the entire book cover. The negatives used were full size, so picture a photo negative about 18x14 or so.
We did some maps in one color, non halftone that were roughly 28x34. again one negative for the whole thing. Yes, the camera was huge. and the room had to be kept very clean to avoid getting dust in the picture.
This page has a few pictures of the dept working on the negatives.
http://www.lithokrome.com/history.aspx
This one has a picture of a shop around 1910 showing the stones.
http://www.flickr.com/photos/steve_frenkel/5145531535/
Steve B