Help needed 98 spec jdm B18C-R rebuild

I have a 91 teg that I swapped a 98spec jdm B18C type R clip into about 5 years ago it was my baby… I need some advise about rebuilding it, I could tell you everything about swapping it in a car the specs and stuff like that but Ive never gone inside the engine. what happened was someone sabotaged my engine buy cutting the timing belt and dropping a nut down the spark plug of #4 piston… the damage delt was minimal as far as I can tell, the piston was cracked but the nut managed to miss the valves, the engine was not run with the nut in it just cranked over… and Im pretty sure the valves weren’t bent from the timing belt being cut because its a none interference engine.

My question is about the pistons… I believe that all four pistons from the factory were all balance to each other within … and because its jdm I think the pistons are shaped different for the higher compression… so how do I go about finding a stock honda replacement… do I have to replace all four piston… and do you have to go up a size with the piston due to having to bore the cylinder walls a little when you do a rebuild…
The engine has approx 200,000 on it and was very reliable, so if possible Id like to try and keep it with its stock Honda reliability…
Any help would be greatly appreciated…

Ouch that sucks,

Who would sabotage your engine like that? I never even thought about that before.

WOW . . . Talk about shady. Good luck with your rebuild.

WOW. If I knew who did that to me I would make them EAT that nut, and maybe a couple more. Thats not just sabotage, thats someone who HATED you.
And to answer your question, I would still pull the head. I always was told Honda engines ARE interference, and if you were lucky enough to NOT bend a valve, you gotta take a look at what other damage that nut could have caused.

I have a ITR engine as well. Best thing I ever did to my car.

Pull the head and have it sent to a reputable machine shop, tell them what happened and have all the valves checked out, not just because of the nut, but because of the mileage too.

As for replacing the piston, you should only need a single JDM ITR piston w/ a new set of rings. Have the cylinder honed and maybe check-out the other rings, again because of mileage.