What's it worth? 1965 273 2bbl engine and 904 trans

A friend bought a 1965 273 and cable 904 about a year and a half ago for $500 off of Craigslist. The seller claimed it had been pulled from a wreck many years ago with 71,000 miles on it. He put it in his 65 Dart that had received a later 225/904 sometime in it's lifetime to replace the original 273. He was glad to pay $500 to get his car back to original.