* The Chevy 305 and 350 are both small-block V8s. They share the same basic bolt pattern on the engine block, meaning many of the same transmissions *can* be used, though the specific transmission and bellhousing may need to match the engine's year and configuration.
* The 454 is a big-block V8. It has a completely different bolt pattern on the engine block than the small-blocks (305 and 350). This means it requires a different bellhousing and, therefore, a different transmission than the small-blocks, unless you use an adapter.
In short: A transmission that fits a 305 will likely fit a 350 (with potential year/model variations needing consideration). Neither will fit a 454 without significant modifications (usually requiring an adapter plate).
