[Chevelle-List] disc brake conversion effect on track width

[Galen and Melissa Love]

At the Midwest Regionals in KC, I talked to a guy in a red 70 SS with 17" Torq Thrust wheels, which are exactly what I've been wanting to put on my '71.  I got the info from him (tire/wheel size, backspacing), but my question is this:  he is running a disc brake setup on the front (stock, I think), but I have the original drum brakes on the front of mine... How would this affect the track width (and therefore the required backspacing) for the front wheels?  Does the disc brake setup widen the track any, or does it remain the same?   Thanks a bunch, Galen