At 7K feet, that 392 Rubicon is going to be down on power by about 15%. If it were me, I'd just be manually shifting the 4runner and keeping it at higher rpms on the grades and accept the fact that strong acceleration in that particular situation will not be it's strong suit.

If power is really bothering you, I wouldn't bother with a naturally aspirated engine or even a supercharged one. Turbos are where it's at. A turbo will increase boost to compensate for the thin air and try to obtain the commanded torque from the ECU. Turbos still suffer from a loss of power at altitude and lag increases, but they don't suffer remotely as bad an NA or SC'd motor. More like 3% reduction in power for every 5K feet vs ~10% every 5K feet for an NA/SC'd motor.