I'm scoring around 600's-650's in math, should I get chungs? Will it help at all
I suggest you do. You're probably getting the last few wrong, which is what the book helps with. The rest you get wrong are probably lower level questions that are probably careless mistakes often too. I suggest you might as well go for it.
Although, to the OP, I find a lot of Chung's tips kinda cloudy without proper explanations. It really assumes you know every tidbit of math and just need to be shown what SAT concepts will be tested. The material's A-1, but the explanations suck.
Cover's nice and glossy with good quality pages in comparison to most SAT prep books. If that matters to you.