I went ahead with the installation and drive swap and everything went perfectly smooth, I now have a functional 120 GB DMS. I did have to shave a bit of the rubber gasket that fits around the drive, but it only took me a few minutes and was an easy fix.
Also, compared to the photos in the description for disassembly of the DMS cart, it looks like Phatnoise has recently added some snap on clips that hold the DMS cart together even after the screws are removed, and it wasn't nearly as easy to get apart as described in the Wiki, but once I understood how they were fastened it was a cinch.
Anyways, thanks for the help, much appreciated.