My 2 cents says to use the lowest numerical gear set you think the engine will pull. But I'm pretty conservative. I don't like spinnin stuff to the moon, because I'm always on a budget and if I blow something all to pieces, it's gonna be a long time comin before I can build something else. Plus, with a 512, you could run some impressive times with a 3.23 gear, so there's THAT. I'm sure you can stand more than that, it was just an example. I think I'd try a 4.10 and possibly even a 3.91......but with that tall tire, the 3.91 might not be enough.