so as I understand it, starting with a l28e leads nowhere. What if I boost it? Im sorry, ive been searching for the differences between the 2 but my searches allways pull up 2000+ posts not related.
second,
The RB25 swap is a big part of this forum, in fact there is a disclamer for ALL RBs so search RB25DET or just RB25 and you'll get the awnsers, and posts of people who've done it. Be prepared to spend the $$$ to get the performance you desire.
Third, The RB30. being in Aus. it would be easyer for you to get ahold of this then us in the states. They're SOHC over there tho. But the common swap is to put the RB26 head onto the RB30block and weld a spot for a new tensioner. There is a company I belive in NZ that does this, and the last time I spoke with him he said about 3500 for the longblock.
If you want to do it yourself they come in a old SUV over there, cant remember the name but its the AUS version of the pathfinder.
He clames he started with 460hp with stock RB26turbos in his R33gts and I think is boasting over 1000.
Become a member on Skylines down under for more info. search RB30 over there.