Turbo parts aren't hard to find from the US. I bought my turbo parts from ebay seller blax240. He doesn't have any turbo parts listed at the moment, but if you send him a message, he may have some in stock. Also got some parts from nzeder (Now if I just had some time to build an engine )
Not sure what the legalities are with an RB swap over here. It might be less of a headache with the traffic dept if you keep the L. Obviously, an RB30DET will make more power, so if power is your ultimate goal don't waste time on turboing the L, But an L30ET should be more than capable of 240HP.