Diff ratio help

I'm sorry 650 hp. and your worried about fuel economy. I would start with 3.91 gears then if you're not happy go into the 410s and so forth but, I do feel 456s is too much. Thats just my opinion and you know what they say about opinions, their like assholes everybody's got one and they all stink. LOL Good luck my friend and follow your own opinion after reading all these very helpful posts.