273 302 318 340 build

So Ive muddled/confused things with my still unknown avenue that Im going. Ive been searching looking at piston options. One factor Im trying to research is the.piston weights and how much total weight difference is allowable before needing to balance the rotating assembly??
I sent Fed Mogul an email about the TRW L2373.030
Said that it was discontinued years ago but still had prints. Weight was 595 grams +/ 10 grams.
He had no info on the pin.
Factory 84 318 stock and 69 318 stock from my factory service manuals is 592 grams.
So 3 grams difference +/- tolerances.
Summit website has no weights that I could see for any of their piston choices.
Anyone know how much difference between all 8 pistons before a rebalance is required?
Thanks

I emailed tech thru Summit site. The KB Silvolite1266C 030. Weighs 778-805 grams. Thats quite a bit heavier than stock (592 ish)