Searching for Birth Father Trevor "Blue"

I'm looking for my birth father, I was adopted in March/April 1973, born on March 24th 1973 to Rachel May Guenole or Rachel May Marsh. Was born in Greymouth New Zealand. My birth mother was separated from husband, met Trevor who was freckled and red hair. Played sax, nick named Blue for his blue eyes. His family was from Napier maybe, mother owned ice cream store, or dairy, father wharfie. They were dating, then his parents took him back up north, possibly doesn't know of birth although knew was pregnant. My birth mothers family worked in hospital, I was named after mothers sister, Vanette. At time of birth, mother had two girls, 6 and 4 years old. Birth records have more information in them , but birth mother won't open them so my information is limited and information from her is sketchy. All I have is his first name and some details of his family. He may have been a apprentice electrician or some trade at time. Please help me find him.......