what do you guys think about this hemi?

There were a TON of Hemi blocks cast in 66 and they were used up through 68 (till they ran out) so the casting date really doesn't mean much. The only to have a shot at what year that Hemi is would be by the stampings on the pad above the waterpump housing. Carbs would be numbered as well as the intake, but they may NOT be original to that motor