Hi Scott - you guys are more knowledgable about these compatibility issues than I am; I'll gladly contribute within my experience though.
Grado is a hybrid design; not moving coil, but not moving magnet either. Grado calls them a moving iron, or variable reluctance design. Both the coils & the magnets are fixed within the cartridge body, the cantiliever actually moves around a very low mass (thus high compliant) piece of ferrous metal (iron) which disturbs the magnetic field between the magnets & the coils, thus producing audio output. If Grado's proposal to increase effective mass of the arm seems like a valid approach, then I would use the low output version of whatever cartridge model you chose. You have the required gain, so why not go with the sonically superior low-output version (fewer coil windings = superior performance). I believe that you would also be less prone to hum & noise pickup with fewer coil windings vs. more windings.
Regarding fixed VTA, try to set up the spacers such that the cart body is parallel to the record surface, or perhaps just slightly negative.
Grado is a hybrid design; not moving coil, but not moving magnet either. Grado calls them a moving iron, or variable reluctance design. Both the coils & the magnets are fixed within the cartridge body, the cantiliever actually moves around a very low mass (thus high compliant) piece of ferrous metal (iron) which disturbs the magnetic field between the magnets & the coils, thus producing audio output. If Grado's proposal to increase effective mass of the arm seems like a valid approach, then I would use the low output version of whatever cartridge model you chose. You have the required gain, so why not go with the sonically superior low-output version (fewer coil windings = superior performance). I believe that you would also be less prone to hum & noise pickup with fewer coil windings vs. more windings.
Regarding fixed VTA, try to set up the spacers such that the cart body is parallel to the record surface, or perhaps just slightly negative.