Murray did he desert in 1856 and are you sure he was in the 60th?
This William Ryan was in an Irish Regiment and ended up in SA in 1871[You must be registered and logged in to see this image.]
In the Englishman's Overland Mail - Wednesday 21 January 1880 a Private W Ryan 4 -60th was awarded his silver long service good conduct medal. Not likely to be him based on your description of him
It is a common name but here are three possible leads for you[You must be registered and logged in to see this image.]
There is N/T of a William Ryan in the SAGS medal roll.
Do you have any more details of the 'Native Contingent' that Commandant Welsh was in charge of bearing in mind the Natal Native Contingent were only raised in November 1878.