the valving difference on the itr shocks versus the LS/GSR is there, but is very minimal. when i was doing my ITR shock/spring setup I asked the same question as you did to a guy on honda-tech that works with/at Koni. He said that he threw them on a shock dyno and the curves were similar.

just search for used itr shocks/springs as a whole from a vendor who sells 5 lug conversions.

the top hat bushings are also different on the type R parts.