Information about the shaft diameter is not particularly useful in evaluating a mixer, since the load carried by the shaft depends on the motor power and shaft speed.  Without that information, little else can be estimated or evaluated.
 
The simple answer to converting from hydraulic power to an electric motor is that the electric motor must be explosion proof, given that you are working with solvents, which are present in most paint.  The motor power depends on the impeller sizes and rotational speeds more than the shaft sizes.  You cannot attach an electric motor directly to the shaft sizes mentioned, so bearing supports or speed reducers are necessary.
 
Without more specific information, about the only answer is that a properly sized explosion-proof motor could replace a hydraulic drive in most cases.


The answers by this expert are based on the best available interpretation of the information provided.  The consequences of the application of this information are the responsibility of the user.  If clarification is needed, please submit a further question.