I'm afraid you're out of luck, blue: Your FAA certificate is invalid because your CAA PPL has lapsed. Even if it had not lapsed, you would still have to undertake an FAA biennial review (line checks don't count) though this isn't really a big deal.
I think you will have to get a new JAA PPL, NPPL, or possibly FAA PPL. This will involve exams and a little training with an instructor... other can tell you exactly how many hours you will need. I am sure that the majority of the required hours can be carried forward from flying the heavy tin.