if you are changing the engine block, you need to modify the regn book. The new engine number will be endorsed over the registration book by excise office.
you shall obtain receipt of engine [ block ] from the seller and verify it from your local cplc to ensure the number is clear.
with the engine receipt apply to local excise office with original file for engine number modification / endorsement.
NUMBER PUNCHING [ tampering ] is Illegal & vehicle may be confiscated at any spot checking