FCP doesn't do a great job of frame-rate conversion.
fastest approach would be to "Conform" the clips with CinemaTools.
this will change their playback rate, so wont work if sync is important, like if the clips are second camera on a music video.
to conform:
open CT. it will ask about databases, just say you want to make a new one, then dont.
go to File Menu > Batch Conform, and point it ant any clip in the folder your Hi-8 media is in.
it'll change all of them to whatever frame rate you choose.
the slower way would be to convert the footage in Compressor.
but really, Hi-8 and 7D?
it's not as if the shots will match in any way.
all the best,
nick
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