Color Space

I need advice...

I am doing some simple compositing for a client. The footage was shot on 35mm film. In telecine they output the color corrected scenes as standard def 720x486 uncompressed Quicktime files. The editor did an initial online with the color corrected scenes in his Avid. He then exported from his timeline only the scenes I needed in Avid Packed Codec compression. He exported each scene both as RGB and 601 color space. I have tried a myriad of color management options (including "None") on both the RGB and 601 files. When he imports my compositions back into Avid, the colors do not match exactly.

Any ideas what we may be doing wrong?

Mac Pro
Quad-Core Intel Xeon
Processor Speed: 3 GHz
Number Of Processors: 2
Total Number Of Cores: 8
L2 Cache (per processor): 12 MB
Memory: 6 GB
Bus Speed: 1.6 GHz
Boot ROM Version: MP31.006C.B05
SMC Version (system): 1.25f4

Scott Skaja
edit/design/animation
http://www.scottskaja.com

when the editor brings my composited files back in, he wants them match color perfectly with the footage he digitized from digibeta.

Scott Skaja
edit/design/animation
http://www.scottskaja.com

correction... in telecine the transfered footage was layed to a digibeta tape. Then the editor digitized that tape into his Avid Nitris DX using the Avid's 1:1 10 bit Uncompressed settings

Scott Skaja
edit/design/animation
http://www.scottskaja.com