Driveshaft will need changing, valve bodies are not interchangeable between the two. Not gonna find an aftermarket floor mount shifter for the 64 Torqueflite as far as I know.

From an upgrade point of view (torque converters, shifters, etc) the later 904 is a better choice.

They say there are no such thing as a stupid question.
They say there is always the exception that proves the rule.
Don't be the exception.