Some enterprising gent has emailed this around the car clubs-

There are some amazing roads following the Waikato River down to there, it would be a brilliant full day lunchrun.

http://busstopcafe.co.nz/

Ah Mangakino the site of the infamous Kiwiburn hippy fest http://www.kiwiburn.com/
Only been via SH27 & SH1 but the road out from Tokaroa isn't bad. Pretty fast & flowing corners.
Lake is pretty warm if you're up for a swim after that long drive too.

I think this was it... been a lot of years since I was down there...