The tensile rods were installed in the 1960s to hold the walls together, countering the lateral thrust of the roof load, to avoid potential demolition.
Now the congregation hopes to remove them as it launches a $1.7 million fundraising campaign.
Other planned restoration work includes reinstating a slate roof and repairing and protecting the stained-glass windows.
Restoration appeal committee chairman Mark Hughes said the committee hoped to have all the work completed before the church's 150th anniversary in 2015.
The church on Cumberland St was the oldest church building still remaining in use as a place of worship in the urban area of the city and had a category one Historic Places Trust classification, he said.
The foundation stone was laid on February 11, 1865.
During the 1960s, the congregation was told the church building was in poor shape and should be pulled down and rebuilt, but they made "a very bold decision" not to do that, Mr Hughes said.
The church walls were leaning outwards and the steel rods were inserted to "tie" the building together.
However, heritage architects and engineers had now said the rods could be removed and roof beams strengthened instead by bonding the walls and roof structure, Mr Hughes said.
They have also calculated the church should be well able to support the reinstatement of a slate roof, to replace the decromastic tiles installed in 1969.
New Zealand actor Sam Neill, who has historic family connections with the parish, will be the patron of the restoration appeal.
The first and second generations of Mr Neill's Dunedin family are memorialised in three stained glass windows above the high altar in the sanctuary.
Mr Neill will be the guest speaker at a fundraising gala dinner at Selwyn College on August 13.
The church and neighbouring hall are used by three different congregations.
