There are other problems with scanning negatives Howard. I've posted this twice on photo.net, and will post it again here in hopes more people will see it.

Color nagative films, although they can capture a wider contrast range the color slide films, cannot store as wide a contrast range. If you compare color slide and color negative films on a densitometer you will see there is a wider range between d-min and d-max on the slide films.

No matter what you do, you cannot not get as good a scan from color negative film as you can from color slide film. That doesn't mean the scans from negative films are bad, just that the scans from slide films will beat them. Given that, why bother with shooting negatives if your intent is to drum scan them?