The general rule of thumb that I employ when dealing with file permissions is this: only give the bare minimum permissions needed. If the user only needs to have 'execute' permissions on a file, don't give them 'read' and 'write' as well.
Granted, my methodology often causes re-assigning file permissions repeatedly as my coding evolves, but I feel very secure that no one is able to perform activities that I do not wish.
So, in answer to your question, it really depends on who is going to be executing your script, and how they are going to execute it. I can't really state for you what permission to assign, as I don't fully understand your situation.