You'll probably lose just a shade of power and fuel economy... BUT, they should fit and look fine. 4x4 and 4x2 Rangers sit at nearly the same exact height, except the 4x4's sport a 2" lift block in the rear.
I stuck with 15" rims on mine cuz I have 15" rims for all of my RBVs and I wanted to not have to think when I order tires as to what rims they're going on, so in my case I just bought a little bigger tire than what came on my Ranger and got a more aggressive tread pattern (Sport King AT). Since I needed a lil extra weight capacity in the rear, I built custom leaf packs which make my 2wd sit pretty much just like a 4x4... truth be told, it's often mistaken for a 4x4, and I've had to argue with a few people that it is in fact a 2wd, including two police officers....