Don’t get confused with the PPM metering. Broadcast specs are ultimately measured by the digital dbfs metering. I have never owned a PPM meter and entirely base my mixes on digital scale, a fixed monitoring level and my ears.
With over 800 broadcast docos mixed to date, I have never needed any other metering scale. They are all approximates and only phons metering is a reasonable apparent loudness measure. PPMs are like an almost accurate digital meter so use digital metering as it is actually accurate and is the basis for broadcast deliverable spec. (yes I deliver all the time to BBC and others in Europe so lets keep it simple and honest for the poor fellow).
You absolutely must have a good compressor limiter which will stop all peak excursions over -10dbfs. FCP is a poor mixing and audio editing tool and my best advice is to go to an audio pro to mix properly. Frankly you won’t stand a chance of getting a mix that has the apparent loudness and dynamics control that a pro with proper tools can achieve.
here is a breakdown of the two most typical broadcast specs in an answer that I prepared earlier along with some repeat info-
https://forums.creativecow.net/readpost/8/982782