Original hipo 289 in car

Can't answer the first question. As to the second question, you can't predict with any degree of certainty a correlation between the engine casting and the car's door tag date. The door tag is a scheduled date. The car could be finished before or after that date by weeks. The block casting number only tells you when the block was actually cast. There is also an assembly date code which is when the engine was assembled. It will always be after the casting date of the block and all other casting dates on the engine (the intake manifold being the easiest to see), by days, weeks, or in rare cases, months. But, the assembly date of the engine can be before or after the door tag date. If after, it is usually not too much after -- a week or two. Engines can be 4 weeks or more before the door tag date, and anything in between. Two months is getting out there, but it is still possible.

When looking over such a situation, it is best to get as many date codes as you can and see if there is at least consistency. For example, if the casting date code of the intake manifold is after the engine assembly date code, then someone has been messing around with the engine. I would be more suspicious of the engine preceeding the car by a couple months in that case. But, if everything is consistent, the motor numbers all look good, it becomes very difficult for someone to state with any authority the engine is not original when falling in a broad range prior to, to a smaller range after, the car's date.

Here is an example of seemingly wrong dates being correct. I have a 65 Fairlane HiPo built in April 1965. The differential tag and casting date codes were July 1964. That's 9 months earlier than the scheduled build date of the car. Easy to say this can't be. When I removed the axle housing and began a clean up on it, I discovered a repair. When the metal was stamped for the center housing, the metal folded over on itself rather than being formed. The stamping of the folded metal caused it to crack in the fold. Probably leaked after assembled. The crack as repaired by welding and the differential surface was resurfaced at the weld. It was a very professional-looking repair. My guess is that after the repair, the axle assembly was rotated into production and wound up in my car nine months later.