I think I saw him conduct at the Met during a performance of Tosca, sometime in October of 1989. It was the finest Opera production I have ever seen. The sets were amazing, including the use of the “elevator stage”, where the set for the dungeon lowers, and the set and background art for the top of the fortress in Rome comes down, during which cast members ascend up stairs in real time. Incredible, at least I thought so.
Very well could have been Levine conducting. The amazing, moving sets you saw were likely thanks to Zeffirelli. He was often criticized by Eurotrash who would have preferred a “daring production” where the singers threw feces at each other and held signs about contemporary politics, but, IMO, no one else ever better understood how a large opera house should be utilized.