Just get one of these, as recommended by Audio Al:
https://i.ebayimg.com/images/g/xpsAA...Yq/s-l1600.jpg
It has a resolution of 0.005g and is accurate to 0.01g. If you don't fit the outrigger platform so the stylus is notionally at the level of the record surface, but place the stylus directly on top of the weighing platform, the error is less than +0.1g. (To be specific using an SME 3009/S2 (Improved) arm, the VTF measured at the level of the gauge platfrom reads 0.03g over that when measured at the record level.)