Digital BW, The Print

Is there a rule of thumb to determine how to adust contrast ranges for 
a print?

i.e. in the darkroom i know how to change the contrast of graded paper 
using a variety of chemicals. With MC papers one changes  the filter 
or dials in a filter change with a dichroic head.

so, if i wanted to go from a print that had a grade 3 contrast to a 
grade 2 and was using +14 as a contrast number(as an example) is there 
a guide line to determine how much reduction i should use?
 Or, are things not so simple?

I don't mind testing, but would like to limit that testing to 5 or 6 
pieces of paper rather than 12.

thanks,
ann