Hi Robert,(posted 8546 days ago)I tried it a while ago with a #29 filter. The EI that worked fine then was 25. I developed the film in Ilfotec HC.
There's a guy at Ilford Germany who seems to to know a lot about the film. His name is Matthias Schneege, and you could mail to him for advice: info.de@ilford.com.
Greetings, Thomas Wollstein