You may also want to factor in what size tires you plan on using. If your going with a 26" tire, like the billboards, or the Mickey Thompson SR tires I'd consider the .68 OD. With the 295/50/15 Yoko's and a 3.46 rear and .82 OD I find I'd like to drop the RPMs a little more on the freeway. Because of that I'm hesitant to drop down to a shorter 26" tire and make the problem worse. Just one more thing to think about
Good luck
Daryl