I think N133 and N140 are your best bet for load data. But I am not sure I checked my VV load guide and they didn't list the 6mm rem. I will look at some of my other reloading manuals this afternoon and see if I find anything.
I currently load N140 under Sierra 80gr Blitz and 100gr Spitzer bullets. The 80gr runs about 3319fps with a charge of 41.2gr and the 100gr runs at 3037fps with a charge of 44gr. I'm looking to switch to the N540 as I understand that it is less sensitive to differences in temperature. My object is to use the rifle in winter varminting and I would rather not be using ammo that loses punch when the temperature dips. I've looked through several load manuals and done several searches on the web for load data and come up empty. My hope was that someone had gone down this road before and worked up a load with the N540 in 6mm Remington. If not, I'd certainly enjoy the challenge of doing so myself. Reading over the properties of N540 do not lead me to conclude that it would not be a suitable application in the 6mm Remington cartridge.