No Kavanagh (or Cavanagh) millers in 1848, also no mention of Alexandra Wharf..
1863 - no mention of Alexandra Wharf..there's a few Kavanagh is possibily related trades :
Edward Kavanagh, corn & flourstores, 14 Mary's Abbey
Jas. Kavanagh, corn broker, 3 Burgh quay, 22 Robert st (stores), res. 33 Harolds Cross
Michl. Kavanagh, corn factor & malt roaster, 3 Pim st
Mrs. Kavanagh, corn factor & malt roaster,4 Pim st, grand canal
I dont see any sign of Alexandra Basin (which I presume the address you mention was close to and named after) on the 1880s map... so maybe it is dates after this that the address relates to ?
Shane