I was able to get through using a stock Pajero on a rainy day in December which turned the track to a very slippery mud - fell on my arse a few times while doing some track building to add traction.
The only mod I have at this point is underbody protection - which I was very glad for because the track is pretty heavily rutted and I bottomed out heavily more than once.
A dry run in a lifted vehicle with bigger tyres would probably be medium grade - or even easy-medium. This is not an easy track and a winch would be suggested if the track is wet.
I travelled East, from Exton's Road to O'Grady's road and there is a fairly steep descent and steep ascent out of the valley. There is a bridge over the Chyser creek. The fun part in the valley is probably only about 1km long.