1971 Demon Sizzler

Hey everyone new to FABO. I currently own a very nice 1967cuda fastback 340 4spd. I am considering purchasing a 1971 demon that the owner claims to be a "Sizzler" car. The car is partially dismantled but in very nice shape. It comes with many extra parts including a complete 340 but not numbers matching. The car is very solid and would be a fairly easy resto. The Vin LM29H1B281793 reveals a 340 Demon/Special Edition. How can I tell if this is a true Sizzler car, and are they (Sizzler Cars) significantly more valuable than your basic Demon. What approx. might this car sell for in the condition described.
Thanks, Jeff