Yes that does help. The DIF confirms that it was cast at Dearborn Iron Foundry and the 49 is most likely the mold number. The vertical ribs were common of service blocks but were also found in some production cars and trucks too. The fact it has the C2 on the maincaps leads me to think it's a 390 as the 428 service blocks had a triangle on the top of the maincaps. But they could have been swapped out for some reason. If you can take a flashlight and look in the water jackets on the head surface of the block for a small "428". You can also knock out the center freeze plug (not sure what side) and look for the 428 cast inside. The 428 inside the water jacket or freeze plug will tell you. The 2U crank is a 66-73 390 iron crank with a 3.78 stroke. The C7 rods are 66-70 428 rods and were also used in the 68 427. A nice HD rod. The thing that bothers me is that you said the bore is 4.13 std 428 right? The .060 pistons don't jive with a 390 bored 60 over to get the 4.13 bore. It would have to be .080 to get the 4.13 from a std 4.05 390 block. Did you get the motor running or apart? It's very possible if it was not running the .060 pistons were just used in order to appear complete. So a little more detective work is required but I think your getting there!!! hope this helps. G.