5.9 Magnum pistons

Hey all. Doing a rebuild on my 5.9 and need a little info. The stock piston have advertised weight of 470 grams which I am trying to duplicate in an aftermarket forged piston or get fairly close. Is anybody running a light weight forged piston similar in weight to the stock piston? I am keeping stock stroke with prob 20 or 30 overbore. If i cant find what is anybodies experience with speedpro flat top hyper pistons? I want to run the serpentine belt system and therefore need the external balanced harmonic balanced with attached surp pulley. Maybe i will have to internal balance if piston weights are hugely different but dont know what i would use for balanced/surp pulley... Thanx