Have a 67 LeMans 326, the engine ID # is 0473147XH and was told not original motor,maybe an Olds. .Was told its a 1969 motor @350hp. I have checked all the various GM code and can find the XH which goes to the 350 in the Pontiac listing but not the numbers. The manifold says Pontiac performance and she has an eldebrock 4barrel(600cfm I think).The 326 had 285hp so I'm lost here. Help please