actually he may not be too far off on that price after i did a bit of searching. It really depends on the shape of the body and such

 

the problem is that the dusters are a dime a dozen. the fact that you have a gold duster makes a difference, as they were rare. if you had a feather duster, you could get even more.

for those who dont know, ive only ever owned mopar and mitsu stuff...

you are correct..a stock 70 318 duster makes around 230hp but keep in mind, that is before the new hp testing was required in the US (that began in 1972, i believe) which they refer to as SAE NET. i would have to see pictures of it to give you an idea...

i own a 1972 dodge demon 340...and i know first hand that the demon is worth a little more, but with the rising prices of E and B bodies, the darts and dusters are becoming more popular with enthusiasts who cant afford 50,000 for a charger or cuda. your best bet to get good money for it would be at a mopar event.