Which would you do? Which would you do if you were going to go turbo in a year or so?
The Type R already comes with LSD. The JDM GS-R comes with optional LSD which I would get if I got the GS-R swap.

Of course the Type R is the superior motor, but I have noticed on dynos that the GS-R seems to have better low and midrange power.

 

For reasons of cost I would go with the GSR motor (Cheaper up front). Which ever motor you go with though, tuning will be the key to getting the most out of your setup. I'm sure there will be those that say don't boost the ITR the compression is to high, you'll blow it up. You can blow up either motor without tuning.

Turbo ITR's can be fun.