It's kind of hard to justify porting and putting in a crank if your motor doesn't even need a rebuild.
When you say prefer dunes, do you like jumping, do you like to drag race, desert ride... What are you trying to accomplish.
If you are pushing the motor to it's max already you need motor mods. If not, you need suspension. If you are happy with it the way it is, make it look good by buying some of that bling bling stuff.