That's one hell of a tall order asking a question like that!
Off the top of my head I would say you need to look at what the a/c has got and then look at what the aircraft needs under JAR
OPS.
You then need to go to a specialist JAR 145 maintenance organisation and ask them to quote for that work scope.
I doubt if anybody on this forum could even start to give you a price for that kind of work. Only you are in a position to look at the aircrafts records then decide on the minimum you need to do to bring it up to JAR OPS standard.
On the bright side - the CAA/JAA usually mandate everything the FAA mandate and vice versa. It could be as little as installing metric altimeters and doing some avionic program pin changes ..... but don't quote me!
