Are you buying a 4 link or a 4 bar, (when the terms are used correctly, they are different ), or making your own?
If you are using a 4 link, with unequal length bars, the approximate center point of the axle swing is at an imaginary point forward of the bars, where an imaginary line drawn through the center of the pivot points converge, and where the axle winds up at any point in is arc it is very dependent on the length and position of the bars in the brackets...(4 links have axle and frame brackets with multiple holes, which allow you to move the rod ends up or down on the brackets to change the anti squat characteristics of you car on launch)
If you are using a set of equal length parallel 4 bars, the pivot position of the rod ends is fixed at the axle and frame, and the axle swings in an arc centered on the midpoint between the upper and lower forward pivot points..it creates a parallelogram as it swings up and down
Either way, it is best to mock up the suspension you are using with the axle and wheels to see where the wheel looks best at the ride height you like. Tack weld the stuff together and jack the car, (or axle), up and down to see where things wind up. If you can, set the bars so they angle down towards the back at ride height... that will give a better ride, and minimize the distance the axle moves forward as it travels upwards. A good rule of thumb is to aim them at the centerline of the crankshaft, at the back of the motor..
If you are making your own bars, the longer the length, the less the axle will move forward when it moves up.
I don't know what year car you are working on, but most post WWII fender openings are not exactly round, so you can cheat some on location. Pre war stuff is really easy to see a wheel in the wrong place. I usually mock up the wheel in the center of the wheel opening at ride height, when it's dropped the tire is up inside of the wheel opening and it is harder to see the lack of concentricity between the wheel and opening.
That's how I do that stuff, it takes longer but WYSIWYG when you are done.
Later, mikey