What do you mean by "equivalent"? The only important thing when comparing different pitch gears is the ratio of the spur to the pinion. If you divide one by the other (doesn't really matter which way round you do it, but always do it the same way) then you'll get the ratio.
It's a simple exercise to do the same with all the spurs/pinions you have in both pitches and then to find the "equivalent" ratio for each combination. 64dp will give you a more granular range of ratios than 48dp or 32dp, though with modern cells it's unlikely that you'll need this as much as in the good ol' days...
You can setup a simple gear ratio chart in Excel/GoogleDocs and print it out (or save it to your phone!) for quick reference.