For a basic peppy street car with the engine you have; I'd go with a shift kit, a constant pressure valve body, and a 2500 stall in your trans, a set of long tube headers with 2 1/2" dual exhaust and some free flowing mufflers all the way out the back. If you don't mind cracking your rebuilt motor open again, I'd go back to the Vortec heads, dual plane Vortec aluminum intake, and something like a Performer RPM cam; just watch the lift on the stock Vortec heads. I think something like .440 is max on the stock heads. That should give you some nice burnout power off the line and good low to mid RPM power; which is what I like for a street car.