401 in a Matador? Humm, that's a new one on me. Obscure no doubt.
However, SD-455 T/As, while fairly rare, are quiet well known and legendary. The '74s seem to be under-appreciated compared to the '73 (ugly 5-MPH bumper no doubt), however the truly obscure SD-455 cars are the Formulas. While most Formulas of that generation had dual, forward facing hood scoops (the early ones were functional, the later ones were cosmetic), the SD-455 Formulas had a shaker scoop just like the T/A, yet they did not have the other "ground effects" that came on the T/As (fender extractors, wheel opening flairs, etc). I can't remember the production numbers on SD-455 Formulas, but I'm pretty sure there were less than 100 each year, '73 & '74.
Demons and 340 Dusters have certainly stayed out of the spotlight over the years. But I remember alot of 340 Dusters on the roads back in high school, hardly see them anymore. Didn't Al Bundy (Married w/ Children) drive a Dodge Demon?
How about a '72 Hurst Olds Vista Cruser wagon? I've only seen one, they made a dozen or so for the '72 Indy 500. 455, bucket seats and a dual-gate shifter, now THAT's my idea of a SPORTS Utility Vehicle.