It's been a long-held dream for Newburn, who only took up running in his late 40s.
He will turn 60 during the American run.
Newburn will arrive in New York next Thursday with three days to prepare for his dream run.
He'll do a bit of running in those days and make some last-minute preparations.
The endurance runner, who now lives in Feilding, has trained hard this year and even after scaling back the training he is still clocking about 200km a week.
"At the end of those weeks I've felt like I've done nothing," he said.
"That's a good sign, it means that the training is right.
"I'm quietly confident but not too confident."
Newburn has been in touch with Guinness World Records and knows what he needs to do to make it official.
"To be quite honest you don't think about the end result," he said. "All you're focused on is the start, getting on the road and probably the excitement of getting going."
He said he would have to control the adrenaline and pace himself in the first few days.
Newburn has had email conversations with Alison Bradley, the New Zealand woman who ran across America in 68 days and who has been able to pass on tips.
"It's going to be fun; it has to be fun."
His run will also raise money for the Koru Care and the Little Heroes Foundation.