David - what you need to think about is how much you are going to use the reel. If this is a once in a blue moon trip, then I would think twice about getting a Stella. It's a lot of money for one fishing trip. On the other hand, if you do this regularly, then a Stella 10000 or a Saltiga Dogfight may be a worthwhile investment - as would a good popping rod.
If you are not going to get a Stella/Saltiga, I'd recommend that you upgrade your drag with carbontex washers. As you're in the UK, the best way to do this is to order directly from Smooth Drag. Get in touch with Dawn there and feel free to tell her I recommended you contact her.
Go to the link and go down the left hand column for carbontex. Near the bottom, you will see Spheros 14000A. You will also need a small quantity of Cal's Universal grease which they can supply as well. Use only a tiny quantity of it on the washers. This is one situation where more is not better! When you install, ensure you put everything back exactly the way in came out. if not, that is a recipe for disaster.
http://www.smoothdrag.com/price.htmlThe carbontex should get your drag to the level where you can handle most fish and SHOULD prevent a metldown on a very big fish. Don't forget that notwithstanding the maximum drag the reel can exert, you can always palm the reel to exert more resistance which you will find most experienced fishos do anyway.
The upgraded Spheros should do the trick but don't expect it to be a Stella.
Good luck with your trip.