Do any of the characters in the VIN number for a 1970 specifically describe the motor that came in the car?

sorry, but no

I would assume by your question that the numbers don't match, but, just in case...........

If the last five numbers of the VIN match the last five numbers stamped on the block you can figure out the original engine option by looking at the 3 letter prefix on the block.

There may be other clues though, why don't you describe the car and what you suspect the original engine to be.