* Type of engine: A big-block Chevy (like a 454 or 502) will be physically larger than a small-block (like a 350). Different engine families within those categories also vary in size.
* Modifications: Are you willing to modify the engine bay (cutting, welding, etc.)? Significant modifications will allow for much larger engines. Without modifications, the fitment is drastically restricted.
* Transmission: The transmission and associated components take up considerable space. The choice of transmission will influence how much room is left for the engine.
* Headers and Exhaust: These are often the limiting factor. Custom headers are frequently needed for larger engines to fit properly.
* Body style: Even within the 1974 Camaro model year (sport coupe, RS, Z28, etc.), there might be slight variations in engine bay dimensions.
While a stock 454 big-block Chevy is arguably the largest engine that might *fit* with minimal modifications (and potentially custom headers), enthusiasts have successfully squeezed in even larger engines with extensive custom fabrication. Conversely, even a 350 small block could be too big if you don't have clearance due to other aftermarket components.
In short, there's no "biggest" without specifying a level of acceptable modification. With enough custom work, the sky's almost the limit, but it will be a very expensive and complex project.
