The clutch from a 350 will not fit a 396 without modifications. The bellhousing on a 396 is slightly larger than the bellhousing on a 350, so the clutch from a 350 will not be able to bolt up to it. Additionally, the flywheel on a 396 is larger than the flywheel on a 350, so the clutch from a 350 will not be able to engage with it properly.
To install a clutch from a 350 on a 396, you will need to use an adapter plate or a bellhousing from a 396. You will also need to use a flywheel from a 396 or a flywheel that has been modified to fit a 396.
