Wow. If it's truly got 24K original, unmolested miles and no rust and a good interior and the motor isn't seized, it's worth a lot just after you hose the dirt off. Has it been in the barn all this time (and importantly, out of the weather?) Do you see any rust bubbling along the rockers or lower fenders? Any mouse damage to interior or wiring? Are there any major dents? What part of the country are you located in? Depending on that stuff, I'd guess $7-8K in 'original pristine' but non-running condition. If you get it running and really clean it up, new brakes, etc, you might possibly find a buyer at $10K or even more, again depending on condition. Z cars, and particularly 240s, have been going up in price in the last few years. Which is maddening as ****, since I used to be tripping over them at the junkyards 15-20 years ago.