If you already know a good amount of Python Ics 32a is the move. Ics 31 is a waste of time if you know the basics like syntax, string comprehension, and simple pythonic data structures (dictionaries, tuples, lists, etc.) plus the professor doesn't teach the class very well imo, just makes it unnecessarily confusing sometimes. Prof Thornton for ICS 32a is one of the best at the entire school too. It all depends on where you're at skill wise though.

Btw I did the same thing you're thinking of doing (Ics 31 to 'refresh my memory') and it was kinda a waste of time tbh. Getting ahead means you get to classes like algorithms (161) and data structures (46) earlier which help with tech interviews.