I have a 1998 chevy 1500 4x4 pickup with a 305 and the 4L60-E transmission. I am swapping the 305 for a 350 bored out .060 over, with one size bigger than stock cam, flat top pistons and my 1998 305 vortec heads (maybe, I want to do that but I may use the 350 heads.) Also considering headers. My question is will I need a custom tune, where can I get that done, how much does it cost, and is it necessary?