Someone I know in New Zealand went through all this but his turbo kit was remains of a half-cut from a turbo Y34. There is no aftermarket turbo kit for Y34 (highly unlikely there would be one available in Japan).
The russians have a forum on Nissans that may be useful. http://forums.drom.ru/nissan-cedric-gloria-cima/
If you want to spend money on parts you'll have to browse endlessly on Yahoo Auctions. There are some nice bits second-hand you just have to be patient sometimes. http://translate.google.com/translate?hl=en&sl=auto&tl=en&u=http%3A%2F%2Flist1.auctions.yahoo.co.jp%2Fjp%2F%25E3%2583%2591%25E3%2583%25BC%25E3%2583%2584-%25E8%2587%25AA%25E5%258B%2595%25E8%25BB%258A-%25E3%2582%25AA%25E3%2583%25BC%25E3%2583%2588%25E3%2583%2590%25E3%2582%25A4%2F26322-category.html
Even if you decided to run your current injectors and ECU, you would still need to source the exhaust manifold, fit an intercooler, all the related intake piping, turbo dump pipe, probably a full exhaust. And there is no guarantee the engine would run well on DD injectors and ECU. There may also be issues with how many oxygen sensors the ECU monitors as well.
In summary, its not worth the hassle or the money. Should have thought about this before you bought the car. Some stageas have the VQ30DD and VQ25DD, theyre not identical to the Y34 engines but there should be enough info on SAU to give you some ideas of what mods you can do for performance.
Personally, I would do preventative maintenance on the car since you just got it (presumably from Japan). My car gained a lot from just changing spark plugs and coilpacks. A full exhaust system would be good, you could fit a shift kit, throw a Z33 LSD into the diff, inspect/clean the intake plenum because its going to be full of shit (theres a thread on SAU about cleaning the intake, but I cant find it)