KB240 is the one. The KB280 is for the 451 stroke setup. That's why the comp distance is so much smaller. Do look into Probe, Icon, etc forged pistons. They're not typically much more than those KB hypers and much stronger. Oh and Icon is KB's forged line. You also can get 1/16" rings with forged pistons which make more power and give more options than the old style 5/64" rings that the hypers use.

This guy has some pretty good piston prices usually.

http://www.cnc-motorsports.com/pistons-1.html