IIRC without going to look at the saved links I have, RB26DETT wrist pins are further up the piston, so distance between wrist pin centre and piston deck is shorter, hence why RB25 pistons don't work on the 26 crank/rods, they'd be way out of the bore trying to occupy the spark plugs space. The RB25 and RB26 rod length is IIRC the same, so the higher pin is used instead of a shorter rod to allow for the longer stroke.
So yah, you're out of luck with pistons, can't use 25's on the 26 crank.