Turbo will be much more of a challenge considering your goals. You need to take into account all the parts, installation, fuel management and tuning to get even close to what you want. I have invested over $3k into my turbo setup and I am not done yet. The last step is a standalone ECU. The whole road has been a bit of a hassle but definitely much more rewarding than if I had stuck with N/A.

If I were you, I would lean toward the swap. It would be the best option for reliability, least difficulty and least amount of down time. You won't get as much power out of it as a well tuned, well matched turbo for the D-series but it has much more potential down the road if you do decide to continue modding once you get to a particular point.

My point is: Stick with the D-series and turbo if you plan on being content once you have reached your goal and don't mind down time, intense frustration, subpar reliability, but a rather rewarding experience once it is done. Or swap if you plan on going further than mid 14's and 200 whp and would rather have reliability, less down time, but less power for more money.