Upgrade time! But what's first?

My Fiero is running pretty sweet. I've got a 3.93 final drive (I think) in the NVG-500 tranny I swapped into it and now I'm looking for more! Question is, what should I upgrade first? I'm looking in to getting some 17" rims and some better, low-profile tires (probably looking at 215/40 F and 225/40 R). I'm looking for both power and handling so please feel free to make suggestions.

Oh, and I'm planning on keeping the stock block. I know swapping is quite popular (and believe me, a 3800SC would be pretty sweet) but I'm interested to see what I can get out of the old girl. Thanks, guys!