I've got 3 100 foot rolls of 36 inch wide Ad Type (another kodak contact paper, lightweight) with dates in the early 70's. I found them in a (dry!) bathtub at St. Vincent de Paul (charity thrift shop) and last time I used any was in the 80's. They've been in storage pretty much since then, and I can't access them easily. I suspect that the storage conditions are not too bad. I sure hope so.
It was a great paper; toned beautifully. The bad part is that the lightweight paper has a way of drying with nasty wrinkles. The only way I could deal with that was to mount them wet using archival paste. I found a print in my files that shows the sepia tone and the wrinkles. The lens used was a 125mm Goerz Dagor on 8x10 tri-x ortho film. The vignette was intentional, I suppose that is obvious.