Under the distributor there is a machined flat area
Towards the starter, the engine serial is stamped into that flat surface, if it matches the number on the door tag then it’s the original engine, the engine serial tells you almost nothing about the engine except for the letter at the front which vaguely indicates it was intended for a truck and not a car
Would have been a 216, have yet to see the rare 235 early low pressure engines in our part of the world
Near the fuel pump raised in the casted surface there will be a 7 digit GM casting number for the block which also helps confirm the engine especially if it’s been replaced
-s
