Have you searched.?
Everything you have asked has been covered.
I assume you you haven't searched.
There is even even an rb30 section.
3 people are currently doing builds , countless have already done it.
heaps of threads discuss the neo head benefits, even over an rb26 head.
How did your tuner pull the 8000rpm figure for the rb30? Based on what?
The info is all on here.
Do yourself and everyone else a a favor and read heaps.
If for some crazy reason you are still stuck we Weare here to help, but constantly going over the same shit gets tiring.