the "A" "B' and "C" stampings on the top pad are in reference to the cylinder bores sizes as referenced by the painted "A" "B" "C" "D" on the skirt of the block

scope as seen in A12's pics above, many small blocks have them stamped on the pan rail for each cylinder

a factory 0.020" over block would be a rare occurrence & I have yet to find a picture of a "yellow" MOPAR industrial engine, got pics?

what kind of acid could be used to wash the VIN surface in an attempt to find the missing VIN?