if you are going with either an rb20det or an rb25det i would definitely go with a 4.11 LSD. you can get a r200 4.11 out of the nissan 200sx turbo from 85-87 i believe but they dont come lsd you would need to put an lsd unit into it. i say a 4.11 because those motors in the skyline gts-t came with 4.375 rear ends so the transmission are geared for that rear end, a guy on hybridz.org is running an rb25det with a 3.70 lsd and 3rd gear goes to about 119 mph, good if u want to be a freeway runner but not too quick reving. as far as the pulsar gti-r motors, yes they are stronger internally and have found out recently that they also have individual throttle bodies, they arent really hard to come by i can probably source one out if needed.