With that carb I can only change the primary (I think it is the primary) jets. It came with 70s and I put 72s in it. So I need to go with 74s?

Edit: I ran the picture of the plug by the engine builder and he likes the color. I've always heard it should be a little brown too but he says his "gas man" says the plug should be the same color as when it came out of the box.... my new Autolites are black, so, I don't think I want that. (some things can be taken too literally).