Are you telling us there exists such a thing?
I am telling you and anyone else interested that I understand that there is - or at least was - such a thing and that he evidently can't remember what he did with it - it dates from around 1955 or 1956.
As for C Matthews, it's a matter of taste I know but if anyone were to orchestrate Sorabji I'd prefer it to be a composer with more imagination than that. (Have you heard Heinz Holliger's orchestrations of some late Liszt pieces? - something further along those lines, for example.)
No, I've not heard those orchestrations and am now agog to do so! That said, I'm quite sure that CMatt would not choose to orchestrate any of OC...
Best,
Alistair