Cannonball1200

I've heard the cranks are not the same, balance anyways, between the 5.3s and 5.7s because of piston weight. Is this true? If so, here is my real question. I'm planning on building a 5.7 from a 5.3 block (complete engine) I already have. I have already purchased an LS6 Crankshaft, I couldn't pass up, with less than 10,000 miles and has been Micro-polished and had the oil holes chamfered. Are there any issues with putting the LS6 crank in the 2002 5.3 block, like reluctor ring between the two, balancer, flywheel, or anything else. Or, should I just get the 5.3 original crank rebalanced and use it? I'm pretty new to the LS engines and haven't seen this subject touched on yet. If there's a sticky on it, I've missed it. Let me know what you guys think.