Kodalith ortho film, type 3

In the mid eighties I used a few boxes of Kodalith ortho sheet film, type 3 . Very expensive at the time.
Used with the recommended Kodak developer it gave solid black and white results.
A home made pin register set up allowed me to get prints showing only solid black, grey and clear white. A sort of poster effect.

Does anyone know of a modern film that would be a replacement for the Kodak sheet ortho film? i.e. two tone black and white.

Must be available in the UK as Postage rates from USA to UK are sometimes dearer than the goods.

Thanks in advance.

There are a number of products at Freestyle labeled as "ortho litho" -- I don't see anything like this at Fotoimpex, but it's a product still used in some printing processes (I have a box of "hard dot" film that's in this class) so you might be able to find something from an outlet for lithography and offset printing. It might be labeled as "half tone" film, or "litho" -- and sometimes needs a special developer to get the sharp gradation between fully clear and fully black.