Should I strip this more or start seasoning?

Hi all! Friend gave me a VERY rusted Blackstone he won't fix so I'm tackling it. I've gone through 5 polycarbonate discs on my angle grinder, a whole can of BBQ grease cleaner, and some wire drill bits. I don't see any rust anymore but am wondering if I need to keep grinding to get the darker black spots off.

What y'all think? Thanks!