Siena: I have no idea how much Rover 75's go for in Nigeria.

But I'd advice you to steer clear of any Rover running the K-series engines.
The Rover 75 comes in I4 or V6, and all are K-series to be avoided like the proverbial plague.

what other type of engines does rover 75 have apart from these K series also can one change the engine to like honda civic engine like the rover 620's comes with them