there is a new feature called apply normalisation gain, this is misleading as it just raises peaks on clips to the same levels, nothing to do with equalising the clips properly
you could use this but remember if you send to soundtrack pro it wont come across as it is a filter and not a proper levels command
any proper sound work is best done in soundtrack pro, try sending out your keyframed levels audio from final cut pro and then use a limiter or compressor to match the dynamic range.
i find final cut pro very very limiting when it comes to sound mixing
lynda.com has some great tutorials on soundtrack pro and its filters as well by larry jordan