[ErikG]

If you can see the tonal issues a s a clear band around 500Hz with no major overtones Try to notch before using Noise Reduction. Notching and NR often compliment each other, not relying on one technique only often helps.

If its to wide to Notch, using spectral repair can do wonders.

After all the extra noise reduction is done, a little multiband expansion can often lower the low level artifacts enough for it all to work.

What I wouldnt give to get really pristine dialog recordings...

Here in Sweden the dialog editors prep and "almost premix" much further than what is the norm in Hollywood.
But only do so after you have experience in hearing how it all translates on a dubstage, and after talking to your mixer.
Undoing can be a mess during mixing.
Make sure that you have speakers that work for you. I find that on Genelecs (wich I hate) I would overwork artifacts and noise and thus have to bear this in mind whenever I do work on them.