Plural Eyes 3 and 23.98

Ok, so here's this question again. I'm working as an assistant editor for a documentary here in Peru. Our editor is in NYC and we are syncing the footage here and sending the project files to NYC. There are identical media drives here in Peru and NYC.

I have had no problem syncing our 25 fps footage. Even with long interviews the sync has been great. However, the company is european and the project is expected to be delivered on PAL and NTSC but because the power frequency in Peru is 60 hertz, it is my understanding, that certain indoor scenes were shot at 23.98 fps to minimize flicker.

At this point I can't seem to find a consistent approach on how to sync 23.98 footage in Plural Eyes. I'm using Plural Eyes 3 and FCP 7. The footage is from a Canon 60d recorded at 23.98 fps. The footage was converted from h.264 to Prores 422 (Proxy). It does appear that our audio, 48 khz, is drifting out of sync.

I managed to sync a sequence by creating an Easy Setup that converts 23.98 to 24 however I have been instructed by our editor to not change the frame-rate. That being said, I'm aware that I can convert our audio to 99.9% of it's original speed and that some people have had results with this method. Anyways, my question is two part. Is there an agreed upon method of syncing audio with 23.98? Is converting 23.98 -> 24fps most effective?

Thanks for your time.