Update
So I decided to do the entire FAA PPL (NOT FOREIGN BASED) which cost me +$1000 (only 3hrs training, TSA clearance, written and checkride) and I spend 2 1/2hrs with the examiner to sort out the paperwork.
One thing I learned was to convert your CAA licence to EASA you do not need a current rating (of course you will not be able to exercise) and a medical which needs to be issued in the UK (so no CAA approved medical examiners in the US).
Maybe someone can confirm, if I'm coming back to the UK in the future that I will not have big trouble to apply for a EASA licence with my expiered CAA JAA licence.
Marcus