Recommended Secondary Proteins?

I’m trying to increase the protein content of my DIY mix, but the combination of my pea protein and cacao powder (I really like chocolate) has me butting up against the limit of how much iron I can put in my Soylent.

I’m trying to decide what I should use to supplement my pea protein and I’m currently stuck between rice protein and PB2. Or alternatively, going with a completely different protein like hemp or something.

Wanted to see if there were still any DIYers on here that would be willing to provide their input.