What did you use to convert them?
What settings did you choose?

In mpegstreamclip the nearest size would be 720×360
Your clips are an odd size = 720×384
SD NTSC is 720X480 or 720×486
Can you convert them to .mov and maintain size?
Do you have a compression program other then compressor?
After Effects?
I would put the clips into (after converted) 720×480 sequence having extreme letterbox look. AE would make it easy for you.
Chris Tompkins
Video Atlanta LLC