I haven't used Ultrafine film, but if it is a dedicated lith film, for pure blacks you will need lith developer. I used to use kodak lith film and developers in the 80s to make pure line work, (no midtones) mostly for text slides for AV productions pre Powerpoint. As I remember, each part of A and B had to be mixed 1+3, the film was developed for three minutes, (or was it 2.45?) which resulted in the film being processed to completion. If it is under developed, you can get a tonal result in lith dev, which is exactly what happens with 'lith' printing, though the developer is much more dilute to control when to snatch it out the dev. You can certainly get a tonal result in print dev.
If using PQ or Dektol, I would expect a high contrast which may well print as pure black on a hard grade, but lith dev is what will give you pure black and clear highlights on the film. I was actually wondering last week if any lith film is still available. Will have to look into Ultrafine. Thanks!