[Jared Hawco] “I don’t want to de-interlace the whole timeline during export”
my advice is to export the entire timeline,
then re-import and de-interlace.
the main reason i do this is that i generally have a fair few motion effects,
and even after you de-interlace a shot or clip, the MOTION is still interlaced, and can look weird.
and if you are still on FCP7, then yes, as Shane says, you are able to use one of the best de-intelace plugins around.
if it’s not still on the market, you could contact Graeme Nattress,directly, and see what you can arrange
https://www.nattressplugins.com/#home
your frame-rate mis-match is certainly worth doing further research on, too.
I’m from PAL land, and cant help there, sorry
cheers,
nick