340 Piston identification. Silvolite?

Marco and nm9 the L2136F pistons are they stock weight for a forged or cast crank or does it matter, I am going to go with these so I don’t have to rebalance, I have a cast crank that would have stock come with the 8.5/1 pistons, would switching to these 10.5/1 pistons is that same weight? or if I run these 68-71 replacement pistons on a 72 cast crank would I need to rebalance? Thanks