Not knowing which way the bevel is running, I'll just mention how the tang is supposed to look after I ask the main question:
Does the tang fit the mortice in the stock? If the answer is no because it is too large read on.
If the answer is yes and it's got a gap between the wood and the metal, you may have to peen the metal to enlarge it. Let us know before you start pounding on it.
The sides and rear of the tang are supposed to have a very slight taper with the largest or widest part at the upper surface. The taper makes the lower area slightly smaller and this smaller area is supposed to fit into the stocks mortice.
A very slight enlarging of the walls or sides of the mortice should allow the tapered tang to fit deeper into the wood.
When the bottom of the tang stops on the bottom of the mortice, the top of the tang should be flush with the surface of the stock and there should be no noticable gaps between the wood and the tang.
I would suggest you study your parts and see if they will meet this description. If they won't, give some deep thought to what needs to be altered before you remove any wood or metal.
Let us know what you find and what you think the best solution will be.
I'm sure that between us we can come up with a good course of action for you.