Here ya go!
14.5 grams
Using a basic effective mass calculator (link below), the Micro Seiki MA-505 has an effective mass of 14.5 grams. It needs another ~16 grams to achieve a new effective mass of about 30 grams. To add 16 grams to this tonearm, more weight at the headshell and more counterweight has to be installed.
https://www.micro-seiki.org/denon-103-project