I was having a simular problem a few years back and finally found "The Ultimate Model Paint Conversion Chart."I'm not sure where I down loaded it from but I think it was a Dutch Model site. The chart ios dated 2003 & is copy write Aaron Spilling. It has it has 11 collums with FS No. RBG values, FS595C Color names, Testor model master No's., Testors name, Testors model master spray No's, Model master acrylics No's, Pactra, Pactra name, Pactra spray, & Extra Color No's. If you can find it it might help as it has FS No's and if there's a Testors, Pacta or Exta paint you should be able to cross reference that paint paint with other conversion charts.
Hope this helps. Remember we do this for fun John the Pom
PS Personally I'm not that pedantic about colour as it's a very subjective quality, Like if you see the Union Jack flying in the morning sun, and then at evening you see the same flag, do you see the same colours; the answer is no. JtP