larry,
i have been out in my shop checking out weights. a stock 292 piston with no pin weighs about 740 grams. and using 28 grams per oz, yours is 784 grams. so pretty close.
tell me again how you lost 1/2 lb per cyl, that i believe is 6 oz per cyl.
on a side note, i weighed some performance 292 pistons.
a je flat top weight was 640 with rings and pin