Chuck, from what I know about the 6x47, it is a good varmint round. However, you will not be able to get the velocity you want with a 70grn bullet. From what I now about the cartridge, you will be able to push the 70grn bullet out of a 26" barrel at around 3150fps. You could probably get 3250 with a 30" pipe.
If I were you, I would look at the 243. The 243 will push a 70grn bullet between 3500 to 3600fps out of a 30" pipe. The 243 will also push the 87grn V-Max at around 3300 to 3400fps out of a 30" pipe. The 87grn V-max is an excellent bullet for varmint hunting and it has a BC of .400.
Also, Lapua makes excellent 243 brass. The 6x47 is an excellent round, however, I am thinking the 243 will be better for what you want to do.
Anyhow, I hope this helped. I am a 6mm guy too. My favorite 6mm is the 6x284, fast and accurate.