Right click it an make sure the Object Level Display performance is also set to High Quality, but also keep in mind that you are not editing pixels in ID and what you are looking at IS a jpeg preview, not the original art. The higher the resolution of the original, the more likely it is that there will be downsampling in the preview.
What you need to be concerned about is how it looks in your output.
When I export it to PDF, the quality seems to be as it should be. So I guess I shouldn't worry about the way it looks in InDesign? The document is quite large (some 225 MB)...
If the object level settings are correct, then that's as good a preview as you'll get.
As one colour line artwork, try at 1200ppi.
Assuming you're reporoducing it at S.S. size.
Also, besides the linked preview being a jpeg Photoshop and InDesign have very different zoom scales. So with something like high res line art the preview in both programs will be resampled differently to fit the screen as you zoom in and out.
In Photoshop the 100% view gives you a 1:1 image to monitor pixel ratio where you see the actual image pixels.
In InDesign if you want to see a 1:1 ratio of a 600ppi image scaled at 100% you have to divide 600 by your monitor resolution/100 to get the zoom level. My iMac has a 108ppi monitor res, so 600/1.08 gets me the 1:1 zoom level that matches Photoshop's 100%—550%.