Won't be tweaking it up at once since it's going to be my daily driver and my route will be around 70 - 80km a day. The stock engine was run on cng and we're switching over to petrol now so my father wanted a fresh start and wanted a swap, the D15B was the most suitable swap in this scenario. Z6 wasn't available here neither was the Y6. But I think even a D15B would be more than enough for a lightweight City and should be a good upgrade to the stock D13 it had.
Turbo later on depending on my mood and well depending on the pocket too 
I had my eyes on the stage 1 cam but we hadn't bought the engine yet so wasn't sure if it would be worth buying since our plans could have changed then, khair hai 