I'd say that getting a second MPA/MPP would probably look a bit odd on your resume. Now, I can understand how it would give you more time to develop and showcase your research skills. You also might even be attending a MPP program that has a wildly different focus than your first MPA, since the degrees are theoretically different to begin with. Still, I think that it's unnecessary. If you are certain after all of your work and education that you want to continue down the public policy route, then go for the PhD. Your odds of being fully funded are much higher through a PhD program, and while I couldn't disagree with George Mason's general economic ideology more, I'd imagine that a PhD in policy there would get you a good shot at think tanks. Of course, if your thread title's emphasis on 'right' is meant to denote your political stance (or economic stance), then my uninformed guess is that GMU would be a great choice even if you had a bit better numbers. However, since the GRE is a fairly painless standardized test (and learnable), I'd study and retake it. I only wish I would have memorized more than 5% of the ridiculous wordlist, since I got a 650 Verbal despite being an English major. The math section is probably more a matter of reviewing basic math concepts. I spent maybe 2 hours going over geometry and advanced algebra principles, since I hadn't taken any math class of any kind in 6 years, and scored an 800 Q on my first PT as well as the real deal. I'd bet that with a bit of study, you could do the same as well.
I don't know if you did earlier, but if you haven't, you MUST download the free GRE PowerPrep software. Wait until you've studied and memorized the wordlist (if you decide to retake), and then take the two PTs included with the software. I scored 800/640 and 780/660 on the two PTs I took, and scored 800/650 on the real test. So...for me it was an absolutely perfect predictor of how I'd perform.
Now, if you got, say, a 770/650/5.5, then I guess you'd have to throw out applications to KSG and WWS as well as to some higher-end PhD programs. KSG and WWS (or even Harris) would probably be the exceptions to my uninformed advice that you not seek out an MPP in addition to your extant MPA.
BTW, I've written for two college newspapers and also contributed little things here and there outside of those gigs, so I understand why beat journalism is such a fun and entertaining fallback .