Say you had a low compression cast crank ext. balance 440 you were putting in a bracket car. You want to put some decent flattops in it so it had more compression. Keeping the stock rods. Would you need to stay w/ a heavy Speed Pro "Six Pack" piston or could you use (what I'm assuming is slightly lighter) Wiseco Pro True Street piston?

Anyone know a ball park weight of a stock slug vs. either of these two options?
How much lighter before it HAS to be balanced?

I usually balance all my stuff w/o question, but this is a real budget buildup.