A 55 would be like 3 sizes over what you have now, that's huge on the pilot man. I can't imagine you'd need to go any larger than a 52.5. Start with a 50 on the pilot & try one size up on the main. I'm not sure eactly what you're trying to do with the plug chop but you can't judge the idle off the plug man, best way to do judge the pilot circuit is from the amount of turns out & throttle response off idle. If the plug is still white then the main circuit is too lean, you can try moving the needle for free or just bump the main jet size. If it's white then you may need more than one size up guy, a white, white plug is pretty lean bud.