I have a thin metal ruler, mm one edge, inches the other. 12" or 305mm.
I drilled a hole/notch one end, so it fits the spindle, starts at zero. just swing it around, pick a distance and location.
reminder: consider parked position clearances when dust cover is on when picking the location.
as for overhang, that ruler can be used for that as well, just swing it around the spindle.
the alignment discs are good for null points, overhang, and I use mine for anti-skate adjustments
https://www.ebay.com/itm/Turntable-Protractor-Alignment-Mat-Phonograph-LP-Phono-Cartridge-Stylus-A-N...
they make specif ones for specific arms, but this works for anything
I drilled a hole/notch one end, so it fits the spindle, starts at zero. just swing it around, pick a distance and location.
reminder: consider parked position clearances when dust cover is on when picking the location.
as for overhang, that ruler can be used for that as well, just swing it around the spindle.
the alignment discs are good for null points, overhang, and I use mine for anti-skate adjustments
https://www.ebay.com/itm/Turntable-Protractor-Alignment-Mat-Phonograph-LP-Phono-Cartridge-Stylus-A-N...
they make specif ones for specific arms, but this works for anything