For what it’s worth, regarding port blocks, I had relatively good experiences with that with a local ISP here. There’s no guarantee, but many ISPs block SMTP to present accidental botnets from sending email and not technical users, so by asking might already be enough to show that you know enough about it to be unblocked.

As for the blocks, many spamlists you can get yourself unlisted. But I don’t know what permanent range blocks may exist in some systems beyond that.