I'm not sure if FFMPEG has any switches for compressing CinePak encodes to a smaller size, this may not be possible due to how differently the codec works compared to more modern codecs. Looking at my CinePak encodes, I've noticed that the audio sample rate makes a difference in file size since you're using raw lossless PCM audio for compatibility issues. For example, a 3 minute 30 second long Cinepak video at 320x240 12FPS with 22KHz audio is 75MB in size while the same video with 11KHz audio is 52MB. If you're OK with a lower audio fidelity, you could try encoding replacing "-ar 22050" with "-ar 11025" for 11KHz audio and possibly use "pcm_u8" as your audio codec if you really want it to be as small as possible.