Yep done that - and you're right about the last 8km. Actually the last 3km up to summit is painful. How ugly a feeling is it when you get up CRB and can see the summit on the same level as you then you come round the left hand bend and plummett down the road and realise that
you will have to climb again to get back up to the summit....this is after the previous 27km of climbing
.
If you want pain up a hill, give Baw Baw a try. Only Hors cat climb in Australia (well technically it isn't because it isn't long enough, but the ave gradient is equal to or more than anything you'll find anywhere).