Can I replace a Kubota V1505 -EF02 with a V1505 ES?
Your KX71-3S should have a V1505-E3-BH-10/V1505-E4-BH-1
The V1505-E3-BH-10 and V1505-E4-BH-1 are both 2300 RPM engines
The V1505 ES engine is an 1800 RPM engine.
So it is a much lower RPM / HP then what you need.
You could take all of the governor assembly out of the engine you have and swap it into the new engine and then it be the proper RPM / HP for your use.
There would also more than likely need other supporting parts like throttle plate and the such.