Audio Issues After Convert from 29.97 to 23.98

So my friend went and filmed a product video on location...for some unknown reason one of the cameras was set to 29.97 instead of 23.98 like it was supposed to be...

The issue is when he tried to convert it from 29.97 to 23.98 to use on a 23.98 timeline with all the other cameras footage. The video looks fine after being converted in Cinema Tools, but the audio is like its in SSSSSLLLLLLOOOOWWWW MOOOOOOOTTTTTIIIIIIOOOONNNN....

Im sure there must be a way people deal with this issue but i don't know how? When I drop the 29.97 clip in FCPX 23.98 timeline, it all works fine for me, but in FCP7 after being converted to 23.98 its causing problems and he only edits on FCP7.

How do you get around this and get the audio to sync up with the video correctly?

Sounds like he Conform and not converted the footage to maintain duration and audio sync you need to convert. Try throughing it at Compressor.