Grant choose the calibre and go for it. The ruger #1 are so versitile. I use one in 45-70 for group 1 BGRC comp with 350 grain woodliegh RN at 2200fps. I have taken a couple of fallow deer and a fox with it. My #1 in 303 has just arrived and waiting to be shot. I did have a 458 win which I had recahmbered to 450 nitro, but during a brain fart I sold it. Still regret it. Ben, I have followed your adventures with your 450-400 very closely. Great stuff.
Let us know what you choose Grant.