You have a bit of a problem.
First off, there is no way that your source media happens to be 23.98, but you edited on a 29.97 timeline? That would be a slight improvement, but you probably still wouldn’t like the solution were that the case.
If your source footage and edit sequence are 29.97, then there really aren’t that many alternatives.
Option A. Find someone with a good hardware Frame Rate Conversion solution, like a Teranex or equivalent.
Option B. Do a software frame rate conversion. If you choose “better” in something like Compressor, and convert from 29.997, the results would be okay for HD broadcast, but may still be questionable for a DCP theatre release. Expect the conversion (for a feature-length project) to take about 3 or 4 days. The difference between “Better” and “best” is not that large, but the render time is x10. So allow a month. (Do it in 4-5 reels, because your Mac won’t run that long on a single task without crashing.)
Option C. Ask if you can deliver a “SMPTE” DCP, which can tolerate 24, 25, and 30 fps framerates — but that is a pretty new approach and is not yet universally accepted.
jPo
“I always pass on free advice — its never of any use to me” Oscar Wilde.