I agree with Paul that it would be a good idea to check the master and slave cylinders first, much cheaper and easier to do than a clutch as well.
From my experience Patrol clutches give little to no warning that they are about to let go which is not entirely consistant with what you are experiencing. Not saying that's it's not your clutch just check everything else first.

Sliding off the clutch in 4th at stand still is a better way to check clutch bite than first gear.

For a turbo engine the Daiken Safari Tuff clutches would be the most popular choice. Not cheap but well proven.

Tony