As far as we can tell, there are currently NO power racks that will fit the G-body frames and be even close to correct. The narrowest we've found is a regular Mustang rack ,but its about 7 inches too wide in the pivot ball area. I believe Stiletto may be able to make a custom one, but they're gonna make you pay, I think they're near a grand.
The narrowed pinto racks are really the only way to do these cars and not get bumpsteer issues.
If you have some really heavy spring weights, and some handling type shocks and swaybars you could use the Mustang rack and never really notice a problem on the street. It's when you start having a lot of suspension travel that you'll notice the bumpsteer.
Mike