Nick, by "cal." do you mean calibrating the montior screen or something else? Yeah, every now and then have to remind myself not to judge colours on the screen, just too many variables, but when the paint choices are revealed via brand label, then I do have a better idea on how to comment.
As far as the Urban's reference charts go over at ipmsstockholm.org, they have no listing of Tamiya paints to use for the Finnish Airforce of 1939-45:
http://www.ipmsstockholm.org/colorcharts/stuff_eng_colorcharts_finland.htm
There is a digital chart here, I only wish that sources that quote FS numbers would include how close or distant that value is compared to the actual paint:
http://www.clubhyper.com/reference/images/finnishdigitalcolorsswm_2.PDF
regards,
Jack