I just started testing my MP777 with a novak HV4.5 so I am only rehashing information I have been told as I do not have enough experience with the novak systems myself but:
Novak systems likes to be geared low, mine is a 9T, I was only able to run for a short time yesterday before it started to rain, but if the engine/ESC stays cool, I will go up from there, I am guessing that an 11T-13T should be ok, but I believe that 16T might overheat the motor.
As for what you need:
buggy (which you have)
Motor/ESC
conversion kit (seperate from the motor, but you seem to know that)
Pinion - RC-Monster, Mega motors, Tower hobbies, Novak all sell mod1 pinions. The only 9T I could find was from tower and isn't hardened, so I have to run the kyosho nylon spur gear instead of a metal spur (it is much quieter this way though).
Batteries - most people go ~5000mAh, I went to 10,000mAh, but I made custom battery trays and like to waste money (atleast that what my significant other thinks right about now).