Welcome to AE86DC Hayden. That's one really clean sprinter there but if you don't mind me asking, how much did u pay for it?
As everyone else will tell you, buy all your suspension gear first, then buy some better tyres as you can still have fun a 4AC'd sprinter if it's rock solid. Plus you won't kill yourself with body roll packed suspension if you went for an engine upgrade.(trust me, it's not good when you feel like you're floating at 110kph)