(Note, I'm just somebody who has also done a database, not any sort of
authority.)
It sounds to me like the old Portuguese is abandoned, so it's good you're
taking it over. If you can't get another source for pt_PT, you might try
merging the old pt_PT with your new pt_BR, or maybe better yet, do a diff on
the old pt_PT and pt_BR and apply that diff to your pt_BR.
For either product, you'll want to come up with some tests to confirm that
you got an improvement, of course.
On hosting, you'll need some way to get your zip file to Kevin Atkinson. If
it's too large to email, then you'll need a web site to make it availble
from. For me, it worked out to be easiest to create an SF account for that.
(You might also try Google Code Hosting, which is intended to be more
reliable -- it wasn't avaialble when I worked on Arabic.) If you have any
sources which are necessary for regenerating your word lists, you'll need a
repository outside of Aspell, anyhow.