Call Dave Rebello and have a conversation with a racing professional! He can guide you in the right direction -mild to wild - ship you what parts you want to buy from him - I, much like you, have a N42-N42 combo with a little Rebello tweeking.........I am still in the break in period from last fall - (damn snow and salt). I would have to think honing would be your very first step with either block of your pick. Start clean and fresh and follow up with a re-build. I did go to flat tops, 240 rods, with a Dave doing all the head work with a mild cam. Dave and his team are great and they know their stuff and will share information with you. He can help a little or a lot - depending on your budget.........he has the goods....check this link out below. http://www.rebelloracing.com/