I don't think there's any mono recordings, except possibly samples (the big "Top of the Pops" sample on "1987", for example) but what about recordings off the radio? Would this work? I know on the web there's a few off-air recordings kicking about - I'm thinking particularly here of a run-down of the chart from summer 1988 with The Timelords at number one.
I tested it with a small snippet of 3PM, converted it to mono and 1:1 stereo, and when I record them back into CEP, both recordings are 100% identical on both channels. Still the question is wether this difference in channel volumes (not too much, but clearly audible and visible) is intentional or a result of its medium. Maybe it's the sheer g-force that pins the needle of the turntable more on the right side of the groove track... ;-) ..::// Thomas