if you can find the FS number for the paints, which should not be hard, here is the chart of which tamiya paint matches that number.
http://www.ipmsstockholm.org/colorcharts/stuff_eng_colorcharts_tamiya.htm
ok just found this it might be more helpful if harder to read... you can find the color from the model, then either look for it or CTRL-F and search the page for the name. it will tell you how many drips of which tamiya paint of each color to mix to make the color.. (or ratio if you need a lot) like XF-2*2, XF-22*1 is a 2 to 1 ratio of those two colors...
http://makete.jware.hr/colors.html
goos luck! the bare metal silver sounds like probably Aluminum on a newer AC... what part is it? there might be a color you could use because the chart didn't have that one in there...