Apart from
http://www.billmacafee.com all I can offer if you don’t already know it, is a list of the spelling used in the tithes, arranged by Parish, I have included afew over county borders because they were there.
1823-1837 Tithes Applotment Books based upon the index work of the Irish Genealogy Hub’s listing for each parish in Northern Ireland, which are quicker to lookup if you know the parish! The relevant original books are in the Public Record Office of Northern Ireland (PRONI) Belfast
Downing, John Townland: Derrycloan Year: 1834 Aghagallon Antrim
Downing, Patk. Townland: Derrycloan Year: 1834 Aghagallon Antrim
Downing, John Townland: Moyntaghs Year: 1834 Aghagallon Antrim
Downing, Patk. Townland: Moyntaghs Year: 1834 Aghagallon Antrim
Downing, Patk. Townland: Ballydonaghey Year: 1826Camlin Antrim
Downing, John Townland: Carrenbrock Year: 1833Templecorran Antrim
Downing, Thos. Townland: Carrenbrock Year: 1833Templecorran Antrim
Downing, James Townland: Killyberry Year: 1828 Ballyscullion Antrim & Derry
Downing, John Townland: Killyberry Year: 1828 Ballyscullion Antrim & Derry
Downing, Widow Townland: Killyberry Year: 1828 Ballyscullion Antrim & Derry
Downing, Dawson Townland: Dunmurry Year: 1825 Ballynascreen Derry
Downing, James Townland: Killyberry Year: 1828 Ballyscullion Derry
Downing, John Townland: Killyberry Year: 1828 Ballyscullion Derry
Downing, Widow Townland: Killyberry Year: 1828 Ballyscullion Derry
Downing, James Townland: Drum Year: 1827 Bovevagh Derry
Downing, Robt. Townland: Lisgloss Year: 1834 Clondermot Derry
Downing, Widow Margt.Townland: Goshedon Year: 1827Cumber Lower Derry
Downing, John Townland: Currin Year: 1828 Maghera Derry
Downing, Alexr. Townland: Dreenan Year: 1828 Maghera Derry
Downing, Eliza Townland: Dreenan Year: 1828 Maghera Derry
Downing, Geo. Townland: Dreenan Year: 1828 Maghera Derry
Downing, Hartford Townland: Dreenan Year: 1828 Maghera Derry
Downing, James Townland: Dreenan Year: 1828 Maghera Derry
Downing, John Townland: Dreenan Year: 1828 Maghera Derry
Downing, Mary Townland: Dreenan Year: 1828 Maghera Derry
Downing, Robt. Townland: Dreenan Year: 1828 Maghera Derry
Downing, Samuel Townland: Dreenan Year: 1828 Maghera Derry
Downing, Stafford Townland: Dreenan Year: 1828 Maghera Derry
Downing, Staford Townland: Dreenan Year: 1828 Maghera Derry
Downing, Thomas Townland: Dreenan Year: 1828 Maghera Derry
Downing, Widow Townland: Dreenan Year: 1828 Maghera Derry
Downing, William Townland: Dreenan Year: 1828 Maghera Derry
Downing, Francis Townland: Drummard Year: 1828 Maghera Derry
Downing, George Townland: Drummard Year: 1828 Maghera Derry
Downing, Morris Townland: Drummard Year: 1828 Maghera Derry
Downing, Peter Townland: Drummard Year: 1828 Maghera Derry
Downing, Tatty Townland: Drummard Year: 1828 Maghera Derry
Downing, Widow Townland: Drummard Year: 1828 Maghera Derry
Downing, Thos. Townland: Drummuck Year: 1828 Maghera Derry
Downing, Bernard Townland: Gullyduff Year: 1828 Maghera Derry
Downing, Samuel Townland: Gullyduff Year: 1828 Maghera Derry
Downing, William Townland: Gullyduff Year: 1828 Maghera Derry
Downing, Dawson Townland: Rocktown Year: 1828 Maghera Derry
Downing, Francis Townland: Rocktown Year: 1828 Maghera Derry
Downing, Henry Townland: Eden Year: 1833 Tamlaght O Crilly Derry
Downing, A. Townland: Glenone Year: 1833 Tamlaght O Crilly Derry
Downing, Wm. Townland: Dargenagh Year: 1828 Termoneeny Derry
Downing, Dawson Townland: Lemnaroy (Bellaghy) Year: 1828 Termoneeny Derry
Downing, Rev. S. Townland: Lemnaroy (Bellaghy) Year: 1828 Termoneeny Derry
Downing, Bernard Townland: Ballymoil Y: 1827 Tamlaght Derry & Tyrone
Downing, John Townland: Ballymoil Y: 1827 Tamlaght Derry & Tyrone
Downing, Jacob Townland::Aughrim Bates and Donnelly Yr: 1825 Artrea Derry and Tyrone
Downing, Bernard Townland: Ballymoil Y: 1827 Tamlaght Tyrone
Downing, John Townland: Ballymoil Y: 1827 Tamlaght Tyrone
Good luck onwards