hey mikesup .
everyone has slightly differing advice on this one because there are so many variables. i have 2 paddles 1 for flat water and 1 for waves i really don't think you can have a effective all round paddle that does both.
that being said there are adjustable paddles that are pretty good and that might fit the bill.
whoever you buy your paddle from will usually let you borrow before you buy ( i know that sam at wind surf and snow does) and this is were they can measure you up and give you the low down on what you might use.
tom

HI Mikesup

My favourite is 7" overhead. I am 181cm and find this great in surf and flat. I searched for a lot of advice before having mine made and though one the same size as yourself is recommended for surf I would avoid that if you have a back issue.
I have had a major back issue which I have blabbed on about in the past and had a back spasm using a shorter one though found it good in the surf (not the spasm that is)
I had a 6' overhead southpoint paddle and found it would get caught in the back part of the stroke on a decent wave sometimes. For this reason I would recommend I high quality paddle. I spoke to Jodie and Woogie in Noosa and they made me a paddle 7" overhead for me with a Kevlar-Carbon shaft. This is a fantastic paddle and the difference between this one and my old southpoint one is very noticeable. It is very light and has great grab on the water. I have been surf with it in overhead waves and it has never been an issue. My back loves it as well. Below is their contact details.

Kia Kaha Canoes & Paddles Australia
P O Box 230, Peregian Beach, QLD 4573
Australia

Tel: 07 5448 3141

Email: [email protected]
Global Website: www.kiakahacanoesandpaddles.com

Cheers
Swanie