Truly, I am so slow, my thoughts are almost useless. But... for the sake of it....
First few laps (traffic aside), I would think the top elites will do it sub 60 minutes. Average Joe might be 1hr 25minutes. Dont be surpised to see a few people coming around in +1.40 though.
I would expect it to blow out to be almost a 2hr lap for me by half way.
It is a big lap.
Raf
EDITED TO ADD - If you have ever ridden Stromlo, its not a big difference to what you have seen before. Trunk climb, Wedge tail, Pork Barrell and Skyline to Luge. All the new western slope stuff is reasonably nice riding on average firetrail, with 4 short sharp pinch climbs. By pinch climbs, I mean steep little 20 - 30 meter sections where I cant keep the front wheel on the ground.