I think we're a little confused.

You must be talking about converting a USDM DC5 RSX-S to a JDM DC5 ITR.

Right?

If that's what you're talking about, there's no "kit" that I am aware of, but any competent person in the business would be able to put together what you wanted.

Converting precisely would be cost prohibitive. It'd be a lot cheaper to get the suspension parts, and then do some USDM work on the motor, like the vaunted Hytech NA kit.