4AGZE is an awesome engine, but it already has a 3SGE in there to start with, why not keep it that way? A 3SGTE swap would be relatively easy if you can find the harness from an ST165 it should be (in theory) plug and play just use your transmission. Same with a later 3SGE Beams motor, except the harness would have to be somewhat modified to fit your chassis.

The 3SGTE would have the highest potential for power down the road but is a bit more maintenance intensive.

The 3SGE Beams would be great because it's N/A so low maintenance costs and it makes 200hp out of the box.

Just my input.