Every Triumph manual ought to at least give the correct valve timing procedure?
I don't know if the Clymer is any better than any other in that respect? I suggest you compare the Clymer instructions with the factory manual instructions?
Just be aware of which camshaft timing pinion keyway the cam is set to, if you decide to remove the cam pinions from the camshafts, although it isn't actually necessary to remove the pinions from the camshafts in order to split the cases.