This work presents a method to transform a four-part chorale in the style of J. S. Bach into a new one. The transformation conserves the harmonic structure of the original chorale which is therefore seen as a harmonic template. Four new sequences of notes which respect the harmonic template are computed to constitute the voices of the transformed chorale. The transformation is performed by running a local search algorithm that minimizes two concurrent objective functions that compute the likelihood of the horizontal and vertical organization of pitches regarding a statistical model built from a reference corpus of 185 four-part chorales from J. S. Bach. Results show that the algorithm performs well in generating voices in the style of J. S. Bach and could constitute a promising tool for four-part chorale chord transformation.