Weeell... if you actually manage to get stable 380V phase to phase out of it, most modern 400V gear shouldn't be too unhappy unless you drive it to an absolute maximum - a well-regulated 380V supply is well within the tolerances of a long 400V run (high voltage drop).
This thing has to have some seriously creative winding though if it actually puts out 120/380V, maybe completely separate windings for 120 and 380V?
