Eric,
I couldn't tell whether those letters were painted on or actually punched with a plastic lens behind them like the other Wayne/M&S 80 script top pumps. If they're painted, I would say they are not factory original. The original painting could have, of course, been done back in the 50s, so it could be "original" even if not a production piece. Is the top plastic? Conoco did put out some pump tops for Wayne/M&S 80s and 90s that were red or green plastic that lit up. I'm assuming that's what this is, and someone has painted lettering on it. Neat looking top.
Some actual script tops (metal top with punched letters and plastic lens) were Conoco Ethyl, Conoco N-tane, Conoco Demand, Sunoco Dynafuel, Mobilgas, and Mobilgas Special.
Wes