What to use between stock and barrel?

I've got my M91/30 apart at the moment refinishing the stock, and I was curious if I should lay down some grease or something between the stock and barrel/other metal components when I put it back together. Would something like this be recommended?

No. You want the barrel channel without grease. There have been threads about corking the barrel hereabouts. You might look that up and see if it works for you.

Else just make sure the wood has been finished so that it doesn't absorb moisture, or dry out.