New mech cam/not removing in spring tricks?

Are your sure that this increased lift won't cause the valves to strike the pistons? You can use lighter springs to break-in the cam if you want. The heavier springs prevent valve float at higher RPMs. They also put quite a bit more load onto the lifters, cam and pushrods. Break-in muight be easier with lighter springs, but if you do this, when you switch to the heavier ones, you should do another cam break-in too.