Ah, so you're just using your foreign ATP to skip having to get a FAA PVT and COMM before getting your FAA ATP.
61.153 says how you qualify for an ATP and one way is
(3) Holds either a foreign airline transport pilot license with instrument privileges, or a foreign commercial pilot license with an instrument rating, that-- blah, blah, blah
I'd say if you can't fly IFR on your foreign ATP reading this you can't use it to get a FAA ATP. But before you spend any money, why don't you contact the FSDO you're planning to use and ask them.