to make the most of it... yes... needed... no... you wont be changing deck height on the block or heads but a couple thou for a clean up... so pushrods would be a no... if you want more cam you may need more spring and retainers to match...
a loose rule is adding 50 cubes negates 10* or duration in a cam... so an already stock cam will now be smaller... effectively...
as long as you dont have valve to piston issues (which the new pistons will already have reliefs) you'll be good as long as you keep static, SCR, and running compression, DCR, where they need to be...