* Body Style: A hatchback Nova will generally offer more room than a coupe or sedan.
* Modifications: Are you willing to modify the firewall, inner fenders, subframe, or transmission tunnel? Significant modifications drastically increase the possibilities.
* Engine Type: A big-block Chevy (like a 454) is physically larger than a small-block (like a 350), even if both are considered "large" engines. A similar-sized Ford engine might have different dimensions.
* Transmission: The transmission and associated components take up significant space. The choice of transmission (automatic vs. manual, size of the transmission) impacts what will fit.
Without modifications, a big-block Chevy (454 cubic inch) is generally considered too large to fit comfortably, often requiring significant firewall modifications and possibly other changes. A small-block Chevy (350 cubic inch or even a 400 small-block) is far more common and fits relatively easily.
With modifications, practically any engine could be made to fit, though the expense and effort will dramatically increase with engine size. People have crammed much larger engines into Novas, but it often involves significant fabrication and custom work.
Therefore, a practical answer without modifications would be a 400 small-block Chevy, while with extensive modifications, far larger engines are possible, but it becomes less a question of "what fits" and more a question of "what are you willing to fabricate?"
