Well, I'd say power's still a major call, considering the J79 pushed 12,000lbs dry and 18,000 in reheat. Meanwhile the F-119-PW-100s are almost the same size (6 inches shorter, 8 inches higher diameter, and 50 kilos heavier) and punch double that, "greater than" 35,000 pounds in afterburner.
While I mentioned before the general difficulty in re-engining a fighter because of envelope, balance, and placement issues...just imagine a Super Phantom with those onboard. Then again you'd have to totally change the intake geometry, wing shape, and ruin the gorgeous look of the F-4 Phantom.
...probably have to add in re-entry tiles as well...