Baz
If he is looking at Tuna, a fast action 9wt is the way forward, it will double up nicely as an allrounder for inshore SWFF as well.
The reel Drag is the biggest issue, not the so much the rod, so look at some of the sale list for a rod, quite often some good 9 or 10 wt bargains about, especially this time of the year.
Budget is the next question.
The depth is another question, this affects the line, most flats to high water (which is where you get the tuna) water requires a nice Tropic spec 9wt intermediate , Rio Tropical II or similar is excellent.
Lots of things to think about, and the Knots are a bit different too
this i am learning all the time, usually the hard way
Sandy