I guess a good indicator for the route would be the approach thru the Loddens. If they're dry then the route might also be dry! However, it is on the SE face which can be cold at anytime of year and probably a lot of the route never sees direct sunlight.
It certainly sounds like a challenge and probably a tough one for mere mortal climbers to get up in a day.
The 1968 team would have been considered the top climbers of the day, and Dewhirst's repeat of the Sydney route ( with Baxter) in 4 3/4 hours is a good indicator to their form.
In the previous month Ewbank had put up Scimatar on Old Baldy and Stranger had soloed Revelations (now considered 17) on Mitre Rock, Araps.
Interestingly Scimitar was graded 17 M3, and was subsequently freed at 18. However there are quite a few mixed/M4 routes that haven't been freed.