Plenty of choices........my vote is for one of the LS series. If it is a real truck (one for hauling) then a 6.0 LQ4 or LQ9 (L92 6.2 cool but expensive). If it is more a crusier that you want some good HP, good for an LS2, LS3, or a LS9
Big Block are fun, but the LS run as hard and can pass gas stations too.