Personally, I have no problem with keeping information
about the source a pg text was derived from, as long as
it is clear that is information about the _source text_
not the Project Gutenberg digital resource.
(For instance, there are places where we call a book "Third
edition"--when it is our first; or mention a lccn which
applies to the source, but not the PG text. From a library
sciences point of view this could be said to make as much
sense as saying that a PG text has 416 pages, because that
is what the source had.)

--and that would be impossible to say accurately, because how many "pages" a PG text has depends on what size type the reader is using. I agree with all you have said here.

 

Anne