MCOULTER - Some things to consider:
1. The braided stainless hose is very abrasive. Do you really want the equivalent of a pack of sandpaper under your dash rubbing around against electrical wires, etc.? You can get high quality AN hoses that are not SS covered, for example, here:
http://www.amfmotorsports.com/goodridgeprod.htm
2. Go with AN-3 rather than a larger size. Easier to work with, especially in the tight space behind the dash.
3. One problem I had was getting the right adapter to connect the new hose to the back of the gauge. The Smiths gauge fitting is a British thread, 1/8 inch if memory serves. The amfmotorsports place has those, and will put the fittings on for you. Or, as others have mentioned, there are kits available.
Good luck.