The Texaco engine was designed to turn a larger prop at slower RPMs than other Cox motors for an RC event that rewarded maximizing the engine run time.    If the plane is very light it may have enough power but I suspect you will be happier with a larger motor.   It just depends on what you want the plane to do.  If you are still learning and happy with mostly going around in circles then it may be just fine.    If you want performance that allows much in the way of aerobatics then a very strong running black widow might be much better.
Bob