Shooting at 30p to deliver at 23.976p

[johansugarev]

Hello
I am shooting a music video in RAW with the 5D mark III and I was wondering about framerates.
I want to slightly slow time down with shooting at 30fps and then interpreting the footage as 23.976fps in After Effects. Is this a good idea, will it resolve in a smooth motion and does it in any way degrade the quality?
Also how much does this slow time down? I've heard it's about 20% but want to be sure in order to sync my audio track. If I speed up the audio by 20% and then slow down the footage from 30p to 23.976p and use the original audio track - will they match up?

[ShootingStars]

Just do the math.
=(30-23.976)/30=0.2008
So it's 20.08%.