If you're going for a stock NA build with only basic boltons then I wouldn't worry about new rods unless you pull them and can see physical damage. Pistons might be a different story, check for damage ans signs of cracked ringlands. If your block requires overboring then you'll have to replace the pistons in order to fill the gap. If the cylinder walls are fine and you can just get away with a quick hone so that the rings will seat then you don't need to replace them.

Erik P.
Official 2GNT thread Hijacker
Some say that he's driven over more Covenant than he's shot, and that his grenades aren't where you'd expect them to be...
All we know is, He's not The Stig... But he is The Stig's Spartan cousin!