Just missing the #'s Matching original engine & trans on a collector car drops it's value like 25% in some cases... Wild a$$ guess, maybe 30% of what a running driving car is worth, depends on what state, how many others are listed at the same time, driving the market value... & overall condition is everything as you probably well know too... does it come with any other needed parts ?? included into that persons selling/asking price.... a U code car will bring more than a non-U code car of course... what kind of condition is the grill, trim, interior, dash & gauges, lite lenses, steering wheel, disc brake or drum brakes/power or manual, rims & tires, A/C car ?? {I'm not sure/can't remember in 71 if you could get A/C with the 6bbl}, console car or column shift, what rear end is it a Dana 60 or a 8.750", even what color it is, go wing or chin spoilers, any added stripe packages, any N96 fresh air hood stuff {if so are all the parts still there ?}, Vinyl roof, condition of the glass, any more rare options etc. {some are far more rare &/or valuable than others}... all that stuff really adds up pretty darn quickly or drops value pretty darn quickly too, if it's not there anymore or it's bad... what does the fender tag & broadcast build sheet say ??, if it still has either one anyway... I'm not sure where I would even start to price it or value it at... photos & more specific information would help allot thou...