sorry, didn't read all the info. I wouldn't shoot at any animal past 250 - 300 yds. They get mighty small out there and too much room for error. I prefer 200 yds and less.
That said, I'd stick with your old 06. If you want more power, you may as well move on up to one of the big mags. I would opt for the 338 WM and never look back. Probably a lot more gun then you need but what the heck.