340 to 372 c.i.

Once you start mixing parts, you have to balance the rotating assembly. KB pistons are lighter than OEM 360 pistons. Guesstimating without actually weighing what you will use is a waste of time. Even the OEM balance job with OEM parts can be improved upon.
Not sure if you can get light enough using forged pistons, like SRP or Probe, and lighter rods, to get rid of the regular 360 counterweights on the balancer and converter. But it would help towards internally balancing and minimizing the use of expensive Mallory Metal.