A friend gave me a Parker Hale 98 that someone had chambered in .300 dakota. I would like to replace the extractor and rebarrel it to something in the 30-06 family. Am I going to have any problems with the bolt face being oversized?

Yes
You would need a new bolt and the rails might be opened up too much to feed the smaller 06 case now.

If you could post a good photo of the rails we could tell you if they have been opened or not.

assuming it was done correctly to 300 dak, you can probably go 300 winmag without much trouble, other than a REBARREL...

you probably won't, cost effectively, be able to go back to 30-06

could also go with a 308 norma mag and stay with 30-06 overal lenght

weaveman