All,
Don't worry about published pivot to spindle distances with arms like the VPI (whose p-s distance can be easily compensated for).
For these tonearms as well as "fresh mounts" (where you're not stuck with a given p-s distance), work from the effective length (bearing pivot to stylus).
The Baerwaald equations will derive the correct pivot to spindle distance and offset angle.
This thread (I believe) as well as several others have described how to measure the effective length of your tonearm with a plain ol' ruler. If you have slots in your headshell, you will be plenty accurate.
At a minimum, use your measurement to verify against published specs. If you're wildly off (e.g. 3 or 4 mm), contact the manufacturer.
Cheers,
Thom @ Galibier