I get this question on almost every request for piston dishing, "How many cc's can I get out my pistons?". When you break it down, there are 2 manufacturers of "off the shelf" 4.0 pistons, Federal and Silvolite. Both make cast and hypereutectic pistons, and as far as dishing goes there is no difference between manufacturers. Piston construction type is available in the FAQ piston page. Find your part # in the list of pistons and it tells you cast or hypereutectic. So for an easy rule of thumb:
Cast pistons (2228, 2229, 677) can be dished to 30cc's
Hypereutectic (3241, 802, 825) can only be dished to 20cc's
I have not had a chance to machine/measure a set of KB 944's so I can't comment on dishing them as of yet.
If one of the moderators could move this to the FAQ piston section, I would appreciate it. Thanks MoFo for suggesting this.