I can't find anything about the minimum grades needed for entry to the LLM?

There is no such criteria. But remember that UPenn is an Ivy League School. Therefore, it will be necessary to have a strong academic background!

Thanks, I'm sure you're right. I just wanted to get a sense for what the minimum might be, as I'm not sure about US law schools. Then could convert it to see if I have a good chance.

As far as I know, the top 10 to 15 and in particular the Ivy League Schools expecting you to be in the top 15% of your class, but of course you have a chance to get in, if you have a strong application, altough you have not been in the top 15%...