Claris CAD can read files created in any version of MacDraw or MacDraw II. Just open Claris CAD and use the File Menu (Open command) to open the old documents.
This information applies to both Claris CAD 1.0 and 2.0.
In addition Claris CAD 2.0 can save files in MacDraw II format. If you select Save As... from the file menu, MacDraw II should appear in the pop up. If it does not check that the XTND system file and Claris Translators folder are located in the "Claris" folder in the System Folder, or located in the System Folder.