Eggs don't really add much flavor to baked goods anyways so you would only have to compensate for the salty iron taste that blood has. If the recipe already has sugar in it then that will overpower any odd tastes the blood has because there wouldn't usually be enough blood to have an overpowering flavor.
The other option would be to simmer the blood in a pan until it begins to thicken, rapidly cool it, and then use it. The iron taste should be cooked out through this process.
I've actually wanted to cook with blood before but it's incredibly hard to obtain, so I didn't know how strong the iron was. The butcher's in the area thought I was insane. And they don't sell it anyway. They could order it, but it's heinously expensive.