vCoconut

I see.. that's good to know! Fingers crossed since that would be my top choice. Congratulations on the UCSF invite and good luck with your interview!

Hi, so I think you have a good GPA and good research background so I think you would be a good candidate for a PhD program, but I do suggest looking at more schools as well because it is better to be safe than sorry. The only Cali school I applied to was USC so I do not have much to say about the ones you want to apply to. I believe they are more on the competitive side so it would be beneficial to look at additional schools who have research you are interested in. I was told that those who want to go into a more industry-based career should go to a school in a location that does have a lot more industry-based jobs so that may be something to consider for an R&D career.
In terms of not having a neuroscience background, that is okay. Use it to your advantage to say that your previous research experience in disease and metabolism will give you a unique perspective of the neuroscience field. Make sure you come across as committed to learn about the field and to complete the PhD, capable of doing independent research, and can think critically. That is more important than what your previous research experience has been.
For your letters of recommendation: Make sure to give your CV and draft of your personal statement to the professors you only took classes with (in addition to your PI) so they know what to emphasize when writing your letter. It could be beneficial to highlight to them what you think is important for them to include, especially those who do not know you as well as your PI. 
Anyways, good luck!