This eagerly-awaited release has just been announced on the Hyperion website:
http://www.hyperion-records.co.uk/dc.asp?dc=D_CDA67905&vw=dcIt's a real shame Zelenski's two symphonies are not extant :(. On the bright side, Hyperion could be bringing out both his PC, possibly coupled with Zarebski's PC, but I have no conformations of this.
As has been pointed out, Zarebski's PC is a mythic work. Mythic as in non-existent. I think there may be some sketches, but that's about as far as it got before he expired.