The rb30 oil pump is a different design to the one everyone is use to seeing and is a much stronger one, so stay off the limiter and you will never have an issue
I was wondering this my self considering most events have a lot of Evos and S chassis cars turning up and they are always welcomed, I don't see why a V series skyline would be treated any different
There isn't a HKS that is close the 2530 anymore,
The GTSS is smaller but best suited to your needs and the GTRS is bigger and are very slow to come into boost and surge down low and do a lot of other things wrong.
But if you want something as close to the 2530 as possible the garrett -5s bolt back on and are close as you can get
GTRs don't come with dash turbos at all, they have a nissan specified turbo built by garrett But the sizing goes in order of 7-9-5-10, I know doesn't make sense or have any order but that just how it goes