Peter,
The linked article and your ratios are obviously a useful starting point but both appear to ignore colour management and what you are using as a working space in PS, or the colour space of a particular image that is being worked on. It is would be expected that the values for different colour spaces, say sRGB and ProPhoto RGB, will be significantly different.
I would guess that the values given in the linked article might be best for sRGB, although the site completely ignores differences between various displays.
Are your recommendations for purple based on a specific colou space?
Regards,
Nigel