I'm not real sure on the numbers, but IIRC the rig in my avatar w/22R had 96 Hp. My 94 4runner with 22RE had 116 or so. Your rig probably runs a little hotter than stock but you can expect about the same difference in horsepower by converting to EFI.
You don't need to rewire to the whole rig. Finding a donor in a junkyard would be the easiest. you will need at least the engine harnes and the ecu, the manifold and everything that attaches to it, either the efi pump or another high pressure pump because the mech one can't keep up, dizzy, exhaust manifold, and possibly the cam. I know that the cams wee different in the efi motors and i am not sure how it will run with the 22r cam, I'd take it too and swap it if needed. This sounds like a lot, but all of the parts are bolt on. You also may have to do a bit of harness fabrication, to get power everywhere it needs to be. ie fuel pump, ecu, o2 sensor, etc.
I don't really see that much of a gain here unless you are planning on rock crawling. I put the weber dual stage on it and was very happy with the power gains.
Anyway, the weber is an easy install, and I think that your results will be very similar.
Good luck,
Dan