I think you need at least 40metres for the first run of pitches.
I have a note that Prelim pitch needs ? 3 maillons to extend the y hhang on one limb (the right) to avoid rub.
Vindication...my note has 50m ...depends where you start i suppose. Going down there is a sling on a block wel out to the left on the 'lip' which makes a good deviation to keep you out of the firing line.
I ran out of rope using 40m for the entrance pitches but was able to down climb the last bit.
There are two deviations on the last pitch . The first is a chock stone behind a flake , the second towards the end off a big block on a ledge L . This eliminates some slight rope run a few meters off the ground and ensures you land well out of the firing line.
A short dynema sling larks footed to the hanger is a lighter option than three krabs or maillons where required..