ok, well aside from using mount kits that are available (mckinney) you could try to source a front clip and use the skyline crossmember. this allows more options for super sweet JDM turbo kits that are other wise useless on an RB swapped 240 w/ Mckinney or custom mounts.

I would also recommend getting an aluminum 1-piece drive shaft made because if you look hard enough you can find places that make em for a very reasonable price (ive heard 150, and to me thats a good price when it holds 350 hp). Besides less rotating mass and faster revs is fun right?

I'm not too sure on how necessary a high flow pump would be, but obviously for HP goals above stock it definately is necessary.

Ultimately, RB swap questions like these have been posted thousands of times on thousands of forums. I'm not harpin, but I am saying a little research goes a LLLLOOOONNNNGGGG way...