That piston is fucked. Is it on no.4 cylinder? Defo from detonation probably where its been top speeded.
The cut outs in the pistons are correct. Its just that Nissan didnt make 2 sets of pistons for 1&4 and 2&3 so they made a universal piston with cutouts for any position.
A DET is a much better breathing engine. It will see 300bhp at the flywheel on completely standard parts with exception of the turbo. You will hit a brick wall on the ET at around 230bhp, where after it will require some serious attention.
This pic may sway you, its a comparison of DET inlet to ET inlet ports:
