The 1953 80" and the 1954 86" had identical siamese bore 2 litre engines. later 86" has spread bore 2 litre engines.
The easy way to tell, is there a paper element (full flow) oil filter canister below the carby (RHS of the engine), if yes that is a spread bore engine. Otherwise get the engine number, it is on the exhaust manifold face at the front LHS of the engine.

