@chai2,
the chester dale collection had a show n the nat gallery east wing about 4 years ago. You sure you dont have a giclee print? they are makin them pretty realistic even with all the gallery tags.
If this is a real painting and its provenance would be right (Chester Dale was an Atlanta collector). THERE IS NO STAUTE OF LIMITATIONS ON MISSING NATIONAL TREASURES.
If you hve been honest (and are not dicking around with us to try to show how smart you are), if you get it to the right owners , there probably is a reward up to 10% of its insured value (That could be several million bucks dude)