You cannot fly commercially on a G-reg aircraft for reward on an FAA ticket, otherwise no one would bother with the long winded JAA route.
You can fly aircraft that just require a validation ie VP-B VP-C or indeed M reg
If you ring the CAA they will answer you over the phone. I suspect you haven't contacted them because you don't want to hear the answer
Why are you going for an FAA ticket? It severely limits your options for employment in Europe.
It is not a shortcut as some people think