there are three buying options:
1 Buy a car already setup
2a Buy a car then build it up your self
2b Buy a unfinished project car and finish it your self
Personally id buy the car already setup and running as it saves you time, but then ur unsure on what exact has been done to the car and how much wear and tear is already done.
buying a car and starting from scratch may be more expensive but you know exactly what has been done to the car and getting to know more about the car. 2b is a combo of both but i guess you would get more background too.
if u plan on road registering the car, a locked diff and cut springs will only lead you to more dismay, but its fine to be on a ke70 for some reason.