What is best VTA for Clearaudio Maestro Cartridge?

I believe Kehut meant to say that proper VTA is achieved when the cartridge body is perpendicular to the record, not the stylus.
Records are cut at an average stylus angle of 15 degrees. Phono cartridges follow more or less the same geometry, however due to cartridge manufacturing tolerances, changes in vertical tracking force, different record thickness and non-standard VTA used by several labels, VTA is best adjusted by ear. A good starting point is with the arm tube paralell to the record.

You may want to make sure that the Maestro's compliance is ideally matched to the VPI tonearm. With a Clearaudio tonearm at 2.2 grams, the Maestro tracks beatifully and does not giggle or wobble when playing warped or off-center discs, a sure sign of optimized cartridge compliance for the specific tonearm mass.
Also, the Maestro is sensitive to anti-skating force. Looking from the front, its stylus will play off-center if the anti-skating is not perfect, which seems to be difficult to set up with your tonearm.
AFAIK 2.0 to 2.2 grans is the correct VTF setting for the Maestro, not 2.5 grams. At 2,5 grams the moving iron will be misaligned with the stationary coils and the cartridge will sound dull and undynamic.
Also, if the tonearm weight pushed all the way forward gives a tracking force of 2.2 grams, do not worry about balancing the arm to zero or ading weights. A counterweight very close to the tonearmpivot will have minimal effective mass, which is a good thing to track warped records..
Good luck