engine flush

I just put a boneyard engine in my Chevrolet Work Van, I did not know the history of this engine as the oil was drained out. Pulled the engine and changed out all components on intake, oil cooler, pulleys, and installed it into my van. set timing hooked up everything, turned the key... engine runs great. This was 2 weeks ago. All I have done since then is change the oil 3 times. Did not open up the block in any way. Truck runs super now. I wouldn't waste the time or money on engine flush. Just change that oil.