Nonissue once he realizes he doesn’t need an oil pump.
There’s no way a JDM EJ has a proprietary Japanese only pump. I’ve installed JDM engines. Don’t think I’ve ever swapped oil pumps on a Japanese motor but plenty of other parts between US and Japan.
If he’s positive it’s the pump it can be resealed. Tighten the backing plate screws, one very commonly replaced oring, and bolt it back up with new RTV
While it’s out the clearances from the FSM can be measured. I mean no one ever does that but if they’re that concerned about it there’s an option