Help..engine Id

FEELING SMUG AT MO AS IVE GOT MY 1956 88 INCH PASSED THE DREADED MOT. ONLY PROB IS ON RETURN TRIP HOME COOLANT HAS STARTED THROWING OUT EVERYWHERE . THE LUCKY ENGINE IS A PERKINS OUT OF A 79 S111 LWB BUT HAS NO MARKING/ NUMBERS ON IT.
ANY ONE OUT THERE THAT CAN EXPLAIN DIFFERENCES I SHOULD LOOK FOR AS NEED TO ORDER A HEAD SET?
PLEASE HELP.

don't shout.

Perkins engine not standard Land Rover so it could be almost anything.