ok from the research Ihave done.
unless your going for mega power forget the rb 25/30 unless you can do all the work your self.
the rb26 crank and rods fit in the rb25 and get some forged pistons if you want to run serious boost or just use forgies on the stock bottom end.
con b4 you do any thing fit the rx6 turbo but make sure its suitable for the rb25 and yes they are very good turbos.
get a power fc z32 afm and bigger injectors merli is making 280 rwkw on a stock bottom end rb25 so you can and when it blows then fix it strong but it could last for ages. If tuned welkl and looked after
meggala