No, I'd bet $50 you cracked the ring land and need a new piston...here's a shot of a #4 piston in a KA24DE after light detonation:
It's hard to crack an iron block, and since the head is good, it's not anywhere above the piston...
I think you need a new or better mechanic...hehe.
Good luck with the rebuild...I reused my rings, rod, wrist pin, and bearing...and it still runs like a champ, except I used the wrong grade piston (and a used one at that!) and that motor is no longer in my turbo car, but it still lives in my daily driver and runs great, with a hint a piston slap at idle due to the wrong grade thing.
- Brian