1973 Duster 340 Clone, Whats it Worth

73SwingerBuild said
That "340-3" number denotes a 340 ci motor with a "3" casting quality. The casting quality is the last digit and is rated between "1" and "8", with "1" being the best casting quality with low porosity. It very well could be out of a 1971. You would need to check the rest of the numbers.

Duster_71 said
I'm learning every day; always thought the last number represented the year of the cast, thanks. So, here is the cast # 2780930-340-3, can you help with that? (thanks)

The fact that this could be a 71 340 seems to make it more desirable to me, should I add that into the equation? I feel bad that I made the error in judgment and told the guy that it was not a 71 motor. I called him and apologized for what might be a mistake.