You have quite a difficult job here. I agree with Shane that he could quite easily been born in the area and no record has survived. I would start as locally as possible, but I do see your difficulty! I noted that you had an Edmund Ryan witness to the Marriage in your earlier thread.
Have you seen the marriage in 1819 on familysearch: (old version)
GI Individual Record FamilySearch™ International Genealogical Index v5.0
British Isles
ANN RANSFORD
Spouse: JAMES RYAN Family
Marriage:
10 AUG 1819 Toem, Tipperary, Ireland
This Ann would have been of an age to be a sibling of George. Maybe worth keeping to one side, if the Ryan connection comes into play.
This account also locates some Ranfords in Tipp:
Nov. 5, 1844
On Wednesday, as a man named John Ransford, was proceeding from Bird-hill
towards Ballynahinch, he was met by a party of armed men who attacked him.
He escaped and ran to the house of a relative Edmond Ransford who informed
the police at the Muragh station, about a mile and a half distant. Sergeant
Goore and a party of police pursued the ruffians who fled in the direction
of O'Brien's bridge. He succeeded in arresting three men, named Martin
Tracy, James Tracy and Hill. The cause assigned for the attack is a spirit
of revenge, instigated by Ransford having taken some land from which the
Tracy's had been evicted. TIPPERARY VINDICATOR.
Just a snippet to keep to one side.
I looked at the Griffits valuations on askaboutireland - there are two entries for George Rainsford in Castlecomber
1 House and lands c. 3 acres Glenmagoo or Fiorda
I house Office and lands c. 18 acres Castlecomber part of. Just wondering if these two are George Married to Elizabeth Price and a possible father, or George and a son. Or one George involved.
The landlord in both cases is Issac Bradley.
I then had a look at the registry of deeds project:
http://freepages.genealogy.rootsweb.ancestry.com/~registryofdeeds/by_name/name221.htmNo George, but lots of other docs.
So realy a dead end, unless you want to spend a day working throuh these Rensford docs to see if you can glean anything. Which you may have done already.
Best of luck with your search,
PM