Take care not to re-use custom variable slots you are australia business email lists using elsewhere in your analytics. You will probably then want to add a filter to your analytics profile to convert the raw referrer into referring keywords using a filter like this one for getting detailed PPC keyword information (obviously not filtering only PPC traffic). You might also want to pull out the original source (which you can work out from the referrer and landing page) into a separate variable.
With this all set up, you will be able to run conversion reports by original keyword for a given original source and see conversion information based on first click attribution. I would expect that you would see the long-tail contributing far more than it does in the standard reports and branded search much less (not zero of course - there will still be first-touch branded searches driven by PR, offline marketing etc.). Multi-touch attribution modelling If you are feeling especially hardcore, you can dig even deeper into this whole mess by attempting to capture multiple touch-points.
The idea here is that you want to give attribution for conversions not only to first- and last-touches but also give so-called assists to touch-points along the way (e.g. a conversion