I have been reading some similar questions here but they are not the same. The project we have inherited from our partner has fixed scope and a fixed deadline to deliver. We are now thinking about way how to manage and agile seems to be the way (providing the framework).
If there is basically nothing left to juggle with, I would say we still could benefit from e.g. Scrum and its processes just to have some management in place. It will not be really agile (in its true meaning) but I cannot see any better way how to that. Waterfall does not make sense as we have cross-functional team where our testers immediately test tasks completed. I would be extremely grateful for suggestions.

EDIT: I will repeat - I am not asking about estimates etc., the project is in its 70%. I am asking whether an agile approach could help to manage the execution - there is a cross-functional team at hand, so waterfall does not make sense (tester could work right away on completed features).