Headshells make a sonic difference, so in the extreme case of audiophile nervosa one would select a headshell not just based on its weight but also based on the materials of which it is made, which affects the sound quality. Therefore, you might want to start with the question of what is the weight of the headshell in the technics tone arm, because apparently the cartridge works well at that headshell weight, just in terms of the net effective mass. Select the AT headshell that approximates the weight of the OEM headshell. Since the headshell contributes in a major way to the overall effective mass of the tonearm, you can’t just select a head shell based on its weight alone, without considering the tone arm to which you plan to attach it.
