Hi kezwald,
The best article I’ve found that states the relationship between Pascal, Newton and softness, without getting “too deep into the weeds”, is this one from European Bedding. I think this has some really good information for you.
Regarding the kPa, there are still variables we don’t know, even the size of the disc being used for testing, and in the end it’s really much easier and more relative to use the density of the Dunlop latex to related the softness. You can see some of the ILD’s for different densities of Latex Green’s 100% natural Dunlop in post #2 here. 65 kg/M3 is generally regarded as a plush Dunlop latex.
Phoenix