The 3.4 will nearly double your rwhp, so yes it would be a night and day difference from the 22r(e). Cost wise, ORS used to charge around $5k for a trun key 3.0-3.4 swap, a shop that is unfamiliar with the swap will likely charge significantly more.
If you don't have a 1st gen straight axle, nor have done an straight axle swap, you can buy a 3rd gen Runner for less than the swap will likely cost.