ignore that NTSC.
it does not relate to HD
“is the NTSC part an indication that they want it at 23.97fps?”
ask them about that.
“how do I turn my 90gb ProRes 422 HQ mov (plus audio) into the new frame rate?”
copy the file,
open it in Cinema Tools, and Conform it to the new frame rate. It’s instantaneous.
the audio will be pitched slightly. maybe not enough to worry about.
but you might not have to do that. Talk to them.
nick