I would go shorter barrel in the truck. - Actually, I like shorter barrels in general, so I am biased in that regard.... no longer than 22".
284...(I am biased there again)
Medium sporter weight barrel, or Magnum sporter contour, non-fluted...I don't know what rocks equivalent here is, but the shorter barrel will be plenty stiff.
Faster twist for the heavy bullets, but a 162 Hornady ain't bad at all.
A rifle like that should come in under 8 1/2#, and that rifle will hunt to 700 and easily hit well past 1000 with slicker bullets.
TC
