Cusdin has won many two-day pro-am events both on the local and international stage but regarded this four-round win in tough conditions as the biggest moment of his golf career.
"To win here against a really top quality field is great," said the 26-year-old.
"It is huge to get my first four round win as a professional. I have been in contention before but never managed it and this win confirms that I am good enough, I am stoked."
The expected charge from 2009 champion Hendry came as he managed a six-under 64 but Paddison was disappointed with his final round even par 70.
Both of them never threatened the lead of Cusdin in the closing stages.
The final round was truncated by a two hour rain delay as rain made the Tauranga greens unplayable. The leaders had played only six holes and Cusdin admitted it was unsettling but just started again.
"We were all keen to get back out there but we just had to wait and make sure that we were ready to go when the rain cleared and the course was playable."
He enjoyed the battle with the 24-year-old Fox who pushed him hard.
"Foxy was playing pretty solidly and put me under a fair bit of pressure. He got to within one shot a few times and was always there or thereabouts.
"I was so nervous coming down the last. I was just trying to lag my putt up to the hole and it was a huge amount of relief to see it go in. It is a great feeling."
Fox, who finished third in 2009 at the Carrus Tauranga Open, paid tribute to Cusdin for his performance.
"Jim played superbly," said the New Zealand representative. "He played like a seasoned professional today."
Fox was pleased with his week that saw him finish as the leading amateur.
"I didn't quite get there but I am proud of my effort this week. I knew I had to make birdie down the last so it was an all or nothing play.
New Zealand representative Emily Perry shot an even par 72 in the final round to defeat professional Charlotte Thomas (73) by four shots on a five under total in the women's event.