The amount of $200,000 has already been raised for the aluminium work, with a $150,000 contribution from Trust House and a further $50,000 from Lands Trust Masterton.
Aratoi Foundation chairman Bob Francis said the rest of the finance would be made up with "other grants in line" and a fundraiser later this year.
"It's pretty exciting. It's going to be wonderful," said Mr Francis of the sculpture.
He said Spires, a 14.5m-tall aluminium sculpture by Dawson in Christchurch's Latimer Square, had been installed for more than two years with no maintenance or cleaning required.
Dawson's sculpture Ferns, which had been suspended above Civic Square in Wellington since 1998, was taken down last year. According to WCC, it had been taken down "due to fatigue in the aluminium, caused by the stresses of movement over time".
Ms Bennett said the sculpture had not been viable to repair.
"The plan is to build a new one that retains the delicate look but is engineered to be as durable as possible.
"Neil Dawson has been working on this with engineers, we are expecting to have his proposal by the end of March.
"Then we will know when it could go back up."
She said the rigging of the sculpture had been inspected annually.
The old Ferns is with the Wellington Sculpture Trust.
Mr Francis did not believe the fate of Ferns would be that of Ascension, saying the sculptures were "totally different".
He had been told Ascension would have a "40 to 50 year" lifespan.
