To find out what powder will work best, for what application are you hoping to use the 168MK's for. Long range?,short range?, glass work? What are your goals?
Details are key.
The other question is what are you shooting. What action?, What barrel and length of barrel. Is it a factory stock rifle or did you have a gunsmith build it for you.
IMR 4064 is fine powder, but if you live where it gets really hot, take care it is NOT teh most temperature resilient powder out there. In the temp extreme zones, Hodgden powders, like Varget do better as they resist teh heat a bit better.