I have a 390 block .030 over, 390 rods, 360 pistons and a 428 cobra-jet crank with 390 gt heads. This set-up is awaiting machine work and is not yet built, I was told that the displacement will be 417 cid when complete. Can anyone confirm this or mabey ran or have this combo? Thanks

Sounds about right to me. A stock 390 bore and a 428 crank will give you 410ci (mid-sixties MERCURY FE) and the .030 over should give you the additional seven cubic inches.