"Joseph's body is changing. His strength is improving. His boxing knowledge is being extended every day. He is already a different and a better fighter to the one who beat Francois Botha.''
Both 21-year-old Parker and Tatupu want to unify the NZNBF belt with the New Zealand Professional Boxing Association belt Sonny Bill Williams won when he beat Clarence Tillman.
That fight was 18 months ago and so far Williams has successfully avoided having to defend the title, most recently ducking a call-out from Tatupu.
Tatupu, who works in a timber yard, will train fulltime during the month before his fight against Parker. He has a nine-win, four-loss record but is known as an extremely hard puncher.
Parker is unbeaten over his six fights.
Parker's promoters Duco Events also announced this morning that they have signed light heavyweight Robbie Berridge to their stable on a six-year deal.
Berridge, 28, is a hard-hitting southpaw with only one loss in 22 fights.