RB25 is a good choice.
But I think some of the major Japanese brands like HKS, Greddy, Tomei ect stock in low quantites some SR parts. Their is demand for it since a lot people have swapped that engine into 240's here. Also there are places you can get new replacement parts. Here's a really good place:
Phase 2 Motortrend
If you go under OEM parts you can get stuff like the gasket overhaul kit ect. Same goes for RB stuff.