I want to build a rifle for F-class and my own personal longrange target shooting fun. Should I build a 6.5-06 or a 6.5 -284. I see from some load data the the 06 will get me about 200fps over the 284 with 160gr bullets, so I am leaning toward the 06. What twist should I go with to shoot these heavy bullets? will 1-8 do it?