none said:
The frankenprint concept doesn't help nail anything down.
No, but at the moment nothing does, we can only speculate until we get a definitive answer. It's just that we shouldn't be so quick to rule out the revised credits as a possible '81 revision, it is after all a time when Lucasfilm bothered to revise the opening shot of the film. We cannot narrow it down to a '77 revision based on one bootleg and one Swedish 16mm print.