I use n165, around the 58.8 gns. Although my rifle is a sauer, 270's tend to be not overly fussy, from what i have seen. Although if you look at the Viht website they do give data out. However should you speed check what comes out of the barrel, they seem very optimistic, maybe they have wd40 reducing the friction ! because for almost every calibre, mine are about 150 feet/second slower.
Good luck