Take it back to the dealer and hound them to pay up for the fix. That's what warranty is for. They will not give you money but should get it fixed so you should pay nothing and get you car back on the road.

Then if you still keen to part with cash, build a second motor and you get the best of both worlds , warranty claim fulfilled and built engine. That way you can take your tiem and build it slowly , look for bargain parts and take the pressure off.

Just a thought.