10* c hubs and 0* steering knuckles would be the first upgrade I would do as they will pay for themselves in tire wear alone! Prior to adding them I would only get a day or so out of a set of sweeps, now I get around 2-3 race days on a set. Rest of the upgrades can be done slowly.
I am using Paolo's set up from the nitro section but with a higher ride height and softer rear sway bar and really like the way it feels. Right now I've got 300k center diff oil but am going to try 500k one day soon.