?? sixpack rod weights? and ly rod weights?

There are two parts to balancing. The first part is equalizing the weights of the set of pistons and pins, and then the big and small ends of the rods. Not total weight - only each end. Once that's done you take those figures and get your "bobweight". That's the weight that is clamped to the crank to simulate the two different systems: the reciprocating mass (pistons, pins, rings, and small end of rods), and the rotating mass (the crank throw, bearing, oil, snd big end of rods).
The second part is the weights are attached to the crank and it's spun. A computer figures the imbalance and the crank counterweights are either drilled to remove weight, or drilled and Mallory metal is pressed into the hole and then welded to add weight. Then the crank w/bobweights are spun again and if more weight needs to be adjusted that's done until it's balanced.
So - applying that to your engine - factory cast pistons are heavy - they have steel expansion limiters and big pins... Plsu - the six pac rods have the thicker beams and heavier big ends. So by running them you run the risk of having to add Mallory. If it's a forged crank engine you can use the six pac rods but to internally balance (to run any harmonic dampener rather than the special 6bbl one) you will have to add weight. If you want to make it cheaper - run the LY rod with a stock piston, or preferrably the LY rod with a hyper piston. then if anything the crank will only need to be drilled and be able to run any dampener.
You cannot change rods or pistons to different models (even stock types) than what you have and not have to re-balance.