After 15 months of smelling each other's presence, seeing shadows under doors, and watching through glass, we had the 2 cats interact face to face. Lots of vocalization and one hit and run initiated by Storm. They both saw the vet this week for mani/pedis so they minimized collateral damage. Storm doesn't want to give up her top-of-the-line status and Sylvester is over the top scaredy cat. It's a good thing they were on the wood floor where there wasn't much traction. That kind of leveled the playing field a bit. Sylvester now runs to his basement lair whenever the breezeway door opens. Just in case.
We tried again but she cornered him under the sofa and held him there for several minutes. They were 12" apart glaring until he blinked and scrambled out to his safe spot.
Now, they both watch suspiciously when they come into the living room, in case. We'll do this again soon but I don't have much hope that they'll be friends. They seem to need a glass door between them to be happy-ish.