For best results, you need to convert the to the ProRes422 codec. The absence of the correct aspect ratio (the 'narrow' issue) is not your biggest problem, getting into a format FCP7 likes, is because H.264 and MPEG-4 (they are related) are not supported in FCP7. Use Compressor - it is designed for the job.
"quicktime/mpeg4/"hdtv 1080i"/4:3 frame size/16:9 frame" size should be
"Apple ProRes 322 for Progressive Material" unless you want is to be interlaced for some reason.
BTW, the reason for the 'narrow' problem is that you asked for a 4:3 frame size to be preserved in the 16:9 (widescreen) timeline.
hope this helps