I want to leave the 255 cams in. All mechanics at my dealership insist that is a bad idea and I should stick with the 259e cams. I don't want to lose low end torque. Why are they telling me this? What is the downside to leaving 255 cams in with a 117 kit? If I go with the 259e cams, will the bigger displacement and higher compression in the 117 kit make up for the late cams early on?
Last question, first: The dyno chart is telling you "no."
On the first question: You should ask the mechanics why they're telling you that. But, I believe you would be setting yourself up for some major pinging and difficult starting as a result of some very high cold cranking pressures. I don't think it would play well with the larger throttle body, either. But, I could be wrong.