Converting FAA IR to EASA
There is no minimum more than the fact that an FAA IR is 45 hours and EASA is 50, so if you did the FAA IR in minimum time, you have to do 5 hrs to fulfill the EASA requirement.
However, that will probably not be enough to lift you up to EASA standard, normally 15 hrs or so will be required. Unless you took the FAA license on a Garmin 1000, then you have to start from scratch. G1000 is too easy and do not give the knowledge to fly analogue instruments.
Additionally you need an EASA Night Qualification.