The "narrowed" is somewhat of a misnomer as it applies to the arms themselves. What's narrowed is the track measurement for the entire front end. Based on a comment you made in the other thread it sounds like you're thinking of only the upper arms? You need to have both upper and lower to "draw in" the spindles. Another way of looking at it is the control arms are shorter, the distance from the chassis mounting point to the ball joint. As an example, the Heidts ones I used on my '36 are 5/8ths of an inch shorter, narrowing the track a total of 1 1/4". Odds are you'll have to shorten the tie rods on the steering rack a small amount in order to get enought toe adjustment.