I recently picked up a '66 Impala. It has a disc brake conversion on the front and the front wheels look like they are to far forward. Is there an adjustment to bring them back or is it a spindle design issue? Not sure what make the disc brake kit is.
Nope the use of disc brakes has no effect on where the wheel appears within the fender opening. Owners of the 1994-'99 Caprice (and Impala SS) always complain that Chevy didn't center the rear axle in the wheel well. Once again appearing to many's taste as too far forward.
There isn't any way short of customizing the body to change it's appearance.
Not sure if they ever did for impala's, but one company does make an offset A-arm set for the Nova that is supposed to improve cornering. Might your impala have tubular A-arms on it? If it does they are aftermarket and that might be what is offsetting your wheels.