Let's look at this Satellite logically: Remove the at-most-$5K engine and the $800 trans/converter combo and what have you got? A $4,000 318 Satellite body with a 3.23 open rear and a $200 aftermarket shifter. Take away the hood and grille and you're down to a $3,000 body. I realize the car is worth more than the sum of its parts but with 35,000+ Road Runners built that same year, a clean 318 Satellite is not even anything special, much less a high-value car.
Is the Satellite gorgeous? Absolutely. Is it worth $20K? Not a chance. Somewhere between $12K-$15K is more like it. I'm thinking this guy's into the car pretty inexpensively, and looking to upgrade to a higher-value body style with numbers if he can make it happen. I don't think he's a scam artist or anything like that. I'd probably do the same thing in his position.