I had Sid at droppedaxles.com do a 3" dropped axle for my '53. With any drop of that amount you'll probably have to do a tie rod "flip" so that the tie rod runs under the springs. With a drop of that amount bump steer is a common issue because the drag link is no longer level. There are several ways to get it level again, i.e., the drag link can be flipped on some models, the steering arms can be modified, etc.
Give Sid a call, he has all the tech info and all the parts you need to do it right the first time and he's a heck of a nice guy to do business with.
