I'm another kiwi and have been to Wellington years ago for racing spots like Eastbourne, Lyall Bay, Evans Bay.
Never sailed Plimmerton, and as I became a better wave sailor there was no point going past Taranaki.
When it blows its windy, the first year I raced there I got schooled in high wind sailing

James at Carbon Art makes awesome boards!
I think at your weight a 105 liter will be ok to start with but you will find yourself eventually getting a smaller board then go 95.
As you keep progressing, ultimately when its nuking a 85 liter will be best size.
You will find smaller boards on Trade Me quite cheap.
Good luck