Good Evening, Bob,
As far as I know, Schiller's on Manchester should be able to provide both Kodak and Fuji E-6 film, even though they have been devoting an alarming amount of space to digital during the last couple of years. Allied Photocolor on Forest Park Boulevard (about a mile west of Grand, north side of the street, across from Goodwill) still does E-6 (at least as of a few months ago) and has a turnaround time of about half a day. I've used this lab for color processing, both E-6 and C-41 for years and never had a problem.
One caveat: the main St. Louis east-west expressway, I-64/US 40, is undergoing major renovation. Schiller's is on Manchester, just a bit south and west of the Brentwood Boulevard interchange with I-64. Allied, on Forest Park, is less than a mile north of the expressway. Construction work and the concomitant traffic problems are well advertised in St. Louis media, but exact locations and lane closures change from day to day.
Konical