If the side pipes are long enough to go to the front of the rear wheel opennings, I think they'd look great on a retro project. Are you gonna do a tasteful retro or an over the top one? I'm planning on a tasteful one for the Challenger ( Factory AM/FM radio with a CD player hidden in the trunk a few period stickers in the windows etc. ) As for the Road Runner, it's over the top time. Old Pioneer 8-Track, Pioneer wedge speakers on the rear shelf, Radio Shack TV Tuner from the early 70's, Stereo 8 reverb, Fuzzbuster, Thrush Side Pipes, Cragar Mags. Way too much aftermarket crap. Shoot me an idea on what you're planning and I'll keep an eye open for stuff to use.
P.G.