I think I found the definitive answer to my matching numbers question.

[SteveSS]

On some cars, there are the vehicles' VIN numbers stamped in full or in part onto the block. You can therefore say this engine block came with this car from the factory.


From the book BIG-BLOCK MOPAR ENGINES, it says,

"Another number you'll need is the engine block stamping. This number gives the code for the engine displacement, year and month of production, performance level, and special equipment. The B block or 383 and 400 cid stamping is found on the right side of the block adjacent to the distributor."


So there is no VIN stamped on the block. If the block was dated after the build date for the car you could say it's not correct but if the dates make sense as far as putting things together you could confidently say this is the original block for this car.

 

[Demonic]

The VIN is only on very late 68 and up blocks. Machined pad on the right side above the oil pan rail on big blocks. Became standard in '69.

 

[RemCharger]

"You could confidently say this motor may very well have come with this car" .

 

[69Coronetrt]

The VIN is only on very late 68 and up blocks. Machined pad on the right side above the oil pan rail on big blocks. Became standard in '69.

The issue of VIN stampings on 68 blocks is under researched. You can find VINs on blocks on cars made in August/September at some plants. When the VIN start appearing seems to depend on the plant.

 

[Richard Cranium]

The VIN on 68 engines was on the bellhousing flange by the oil pressure sender.

 

[toolmanmike]

"You could confidently say this motor may very well have come with this car" .

"Date code correct" if it's built earlier than 68. I get a charge of those that say "numbers matching" when they are describing their 64. They also mention it was a "frame off restoration", and it has a Posi in it.

 

[YY1]

That's the beauty of pre-(some date in) 1968 cars.

...and a potential curse for post- (some date in) 1968 cars.