Sounds like you still have factory powertrain warranty. If you have proof of oil changes take it to nissan and they should replace it for you free of charge.
Failing that. The MR20 is a simple swap. I have one in my car. Using the stock Versa ECU, transmission, and all
Failing that. The MR20 is a simple swap. I have one in my car. Using the stock Versa ECU, transmission, and all