Hi,
Looks like he went to Australia with his sister.
LEWIS Benjamin 1841 21 Caher John L. / Catherine ROURKE Father = a clerk . Protestant . A shoemaker. Ship = Susan
LEWIS Sarah 1841 19 Caher John / Catherine both dead .Turned 19 on May 25,1840. Bro= Benjamin on board . Ship = Susan . Protestant
Caher is in the south part of County Tipperary.
I have checked the Tithe records, these are from 1823 to 1837, no John or Catherine Lewis listed.
In Griffiths Valuation there is a John Lewis in Castle Street in Caher in 1852. (Poss brother?)
Civil records were introduced in 1864,deaths before then were not listed unless by luck ou see any.
With the name of the ship the SUSAN, check the TROVE site that you have in Australia for the details.
Cheers
Margot