Here is the best workflow for the highest quality. SInce you have a low TRT (75 minutes) set up a CBR encode in Compressor. Make sure you keep frame rate and field dominance the same as source. You can set the bitrate to 7 Mbps. You will also need to encode the audio to ac3 (Dolby Digital) stereo is .192 Mbps.
Instead of exporting the QT movie out of FCP use Export to Compressor, this will tie up your system (both FCP and Compressor for the entire encode but it gives the best encodes from Compressor). When you do it this way your footage does not have to be rendered first.