Conoco switched to ad glass in the M&S 80 around 1953 when they introduced "Super" as their premium grade of gasoline. While I have not tried to restore an M&S80, I have looked for ad glass for an earlier pump (Tokheim 36B) and I found that very very little was available in the reproduction ad glass for Conoco gas pumps. Here are two photos that show the ad glass in "Super". I believe the first one is the regular top for the M&S 80 and I believe the second one is a fiberglass insert in the ad glass section......but I am not the expert on the two varieties of M&S 80 tops.

UNK - (Andy Williams, Lessee  Edmond, OK?)  {ICE R}  [Todd Helms Collectors Bible] in 1955  <M&S 80>.jpg UNK - (Illinois)  <M&S 80>  Red Triangle Magazine 1957 Jan:Feb.jpeg