The challenge lies primarily in the TBI system itself. It's not designed for the increased airflow and fuel demands of a turbocharger. You'd likely need to upgrade to fuel injection, potentially a different intake manifold, exhaust manifold, and a considerable amount of custom piping and tuning. The cost and complexity of such a project often outweigh the benefits for a relatively low-power engine like the 305 TBI.
In short, while not impossible, it's impractical to turbocharge a 1991 Camaro RS 305 TBI without a substantial investment of time, money, and mechanical expertise. It would be far more cost-effective and easier to swap in a more powerful engine or focus on other performance upgrades suited to the existing engine.
