alright man..
Keep the d.. I would probably go turbo in your situation since it looks like you're just looking for more power and wont auto-x or road race. You're going to be satisfied with it after its done, AND you said you dont want to swap motors.
As far as suspension, get ground control sleeves and Kyb Agx's (if you're low on $), Tokiko Illuminas, or Koni Yellows (best option, but pricey). I have Agx's and it rides pretty smooth with very very little bouncing. You said you wanted your suspension like the car with the c8's, but if you're delivering pizzas, that's not going to work. Your front lip and oilpan are going to get taxed by speed bumps and large hills, so "dumping" your car isnt a great idea, plus you limit your suspension travel (= worse ride quality) by doing it. I would just go with a tasteful drop (2.5 or so) and be done..
and at the place I work, the owner refuses to increase the delivery charge.. our prices are high enough as it is