I think the thread you refer to is this one?
http://www.ukmonster.co.uk/monster/s...oberon+leaking
There's a lot in there about the pushrod and also the tunnel in which it sits, regarding oil passage through it... Well worth a read. it has an easy solution to pushrod spin.
Commando owners with the AMC 'box, sometimes cut the rod and insert a 1/4" ball bearing in there, but this is supposed to stop gearbox oil migrating into the clutch and is nothing to do with anti-spin.
But taking a leaf out of AMC's book.. The actuating end of the rod is pushed by a giant 1/2" ball bearing. It begs the question; could you get a ball bearing into the hollow slave piston for the rod to bear on?