In the state of California, the only smog legal simple bolt-in swap would be a D16A1 from an '87 Integra, assuming you have an Si.

An '86 bolts in the same, but the smog inspector will probably reject it for being older then the chassis.

Any Civic/Integra based B-series can be swapped in but it will cost a lot of money.

If your car is carburated, don't bother with modifications. Upgraded carbs will never pass smog and fuel injection conversions are a pain.