Phono Protractor. Recommendations?

I have a Feickert and a Geo-Disc , if you can see the exact pivot point the Geo is very near  as accurate , but as wlutke says , that's a big if , but some  do make it easy like the Pioneer  PLX-1000 .

The piece of paper Shure put  in on the 97xe was better than either but only for that cart .

I hav a Smartractor and Geodisc. The Geodisc is approximate and good for most applications. The Smartractor is outstanding and very precise.

@wlutke 
How do I find what the correct "pivot to spindle" distance is supposed to be?  (My TT is a VPI Classic 3, my tonearm is the JMW 10.5).

If you want the best, and have multiple arms, get the SMARTractor. 
If you want the best, and have one arm, get the Mint. 
If you want to throw away $20, get the Turntable Basics protractor. 

louisl,
Your spec is most likely 258 mm. Remove the arm and measure pivot spike to spindle center for the actual.