There aren't any great conversion charts for Tamiya to MM paints.
You are better off using the Tamiya chart found here:
http://www.ipmsstockholm.org/colorcharts/stuff_eng_colorcharts_tamiya.htm
Use the FS number and use these charts to try and find a match.
http://www.ipmsstockholm.org/colorcharts/stuff_eng_colorcharts_fs.htm
http://www.ipmsstockholm.org/colorcharts/stuff_eng_colorcharts_modelmaster.htm