I have created a preliminary chart of mouthpieces that are what I consider to be appropriately sized for contrabass trombone. Not all of those listed are specified for the contrabass trombone. Note that most, if not all, of the mouthpieces listed with the contrabass trombone (cbt) shank can be ordered with the smaller bass trombone shank, also.
I would not say that I recommend using a standard bass trombone mouthpiece on a contra, as each is designed for its specific purpose, but if it works for you, by all means, go with it.
For example, I normally use a Griego .25 (which is listed in the chart) on my bass trombone. It is a huge mouthpiece by any standard. However, I do not like the way it plays on the contra. I prefer the Kanstul 2A that came with the horn (at least to the .25).
Contrabass Trombone Mouthpiece Comparison Chart I sorted it by cup size in Millimeters.
If you would like to add to or help me correct this chart, please contact me here.
Comment below with the mouthpiece you play on your contra and how you arrived at that decision.
Thanks!
The Contrabass Trombone Resource 