Hey -- Scotch is much better than bourbon.

For props in the mid-size range (10-14") , & going from 2b to 3b, -- reduce the diameter by 1" for the same pitch, or maintain the same diameter & reduce the pitch by 2". More or less -- assuming that the manufacture is the same, -- assuming that the blade shape & aspect ratio are similar, -- assuming that the material & blade thickness are similar -- otherwise suck it & see.