Lol you do worry 2 much!!

Just cos the guy you bought it off thinks the guy before him might have stamped an A14 with an A12 engine number doesn't mean you have to get this engineered.

As far as you can tell, and that anyone can prove without pulling it down, including youself, the engine is an A12.

Best not to worry.

I would think that if you tell them you have an engine with funny numbers they would have to take the engine off you as it could potentially be stolen or some crap like that.

You are gonna rock up to the engineer an he'll be like u want me to engineer the original engine in the car??? Sure man give me $88 and off you go!!!