Colleen, how far into your project are you? Is it possible to cut in a 23.976 project, given that the bulk of the material was shot at that framerate? If you cut at 23.976 the stuff that I presume was shot at that rate, then have the 60fps footage transfered frame for frame without conversion, you’ll get your slomo. By cutting in a 59.94 project, your 23.976 material is being converted to play at 59.94 and your 60fps footage is already playing at speed.
Once you’ve completed your edit, then output to tape at 59.94 for mastering.
Chris