* Different Bellhousing Bolt Patterns: The Cadillac big-block and the Chevy small-block have completely different bellhousing bolt patterns. You'll need a custom bellhousing or an adapter plate to mate the transmission to the engine.
* Torque Converter: The Cadillac torque converter is designed for the higher torque output of the big-block. Using it with a 350 might not be optimal and could lead to performance issues or premature wear. A converter designed for a 350 with a Turbo 400 is needed.
* Flexplate/Flywheel: The flexplate (or flywheel if you're using a non-automatic setup) will also need to be matched to the Chevy small-block.
* Driveshaft: The driveshaft length and yoke will likely need modification to fit the new setup.
* Additional Modifications: Other potential issues might include oil pan clearance, starter clearance, and potentially exhaust system routing.
In short, while technically possible, this is a significant undertaking that requires machining skills, fabrication abilities, and a good understanding of automatic transmissions. It's not a project for a novice mechanic. It's often easier and cheaper to source a Turbo 400 already configured for a small-block Chevy.
