There's also a Japanese Diesel piston that will work in a 270- - - - -don't remember the metric bore equivalent right now, but the very thick piston crown (about 1/2") can be whittled on to get the right compression height and eliminate most, if not all of the oddball contours. They're still lighter weight than a stock GMC piston.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!