Numbers Matching
The bad thing about pre-1968 Moaprs- they can't be verified as "matching numbers".
The good thing about pre-1968 Mopars- they can't be verified as "matching numbers".
If you have a later cast engine or block that someone swapped in, finding a "date code correct" block is MUCH easier than trying to find a one of one stamped "matching numbers" block, or even a warranty block.