I wouldn't be too concerned about the key adjustments not being equal. Torsion bars wear out over time like any other components, they normally don't wear at identical rates. The fuel tank is on the drivers which could have stressed the drivers side torsion bar slightly more than the passenger side causing the adjustment differences. Are you 2wd? If that's the case buy some lift spindles, they're cheap. The rubbing sounds like an offset issue. 305/50/20 is a small tire (less than a 1/2" taller than stock) and it shouldn't be rubbing unless you are running a crazy offset. I was able to run 33x12.50x20s on stock suspension (keys NOT cranked at all, just how it came from the factory) with only minor rubbing at full lock in reverse. After I keyed the truck I had ZERO rubbing. What kind of offset are you trying to run?