Swapping to a different engine would require extensive modifications, including:
* Engine Mounts: Fabricating or adapting new engine mounts.
* Transmission: Sourcing a compatible transmission.
* Wiring Harness: Significant rewiring or possibly a complete custom harness.
* Engine Control Unit (ECU): A compatible ECU and potentially tuning.
* Exhaust System: A new exhaust system would be needed.
* Driveshafts: Possibly needing modification or replacement.
While technically possible for someone with extensive mechanical knowledge and fabrication skills, it's generally not a cost-effective or practical modification. Sticking with a rebuilt or used 1.9L Ecotec is the most sensible and straightforward option for engine replacement in a 2002 Saturn SL1.