well
only way to get much power out of the N/A 2.3 is some head milling and porting or gutting the intakes..... which would still be more expensive than the swap...
i found my motor for 200 bucks
basically anything you would do to a v8 you can do to a 4cyl car too..... mill work,rocker cam ,cold air intake , larger throttle body you name it....
i got a 210 hp 88tc motor for 200 bucks..... the headwork would prob cost about the same on your work and would maybe net ya an extra 10 hp putting you up to 100hp........
so make a goal for what ya want for your car !