§ 4208(b) preliminary commitment

it is plain that as far as the sentence is concerned the original order entered under § 4208(b) is wholly tentative. That section merely provides that commitment of a defendant to the custody of the Attorney General 'shall be deemed to be for the maximum sentence,' but does not make that the final sentence. The whole point of using § 4208(b) is, in its own language, to get 'more detailed information as a basis for determining the sentence to be imposed * * *.' It is only after the Director of the Bureau of Prisons makes his report that the court makes its final decision as to what the sentence will be.