Here is one already done.

Rb30 With Nitto 3.2 Short Motor - For Sale (Private Car Parts and Accessories) - Skylines Australia

scroll down to last post, convert to carby.

Thats the one

Wouldnt an n/a 26/30 need a fair bit of work to up the compression? i think its like 7:1 or something when both are put together. good for a turbo car but weak for an n/a. Custom pistons/head/shaving may be in order.

But keep it turbo and its an easy conversion almost as simple as bolting it all together and having a mental motor

If I had coin and patience I'd look for an RB26DE

autech made a na version

Yeah but they're rare as. Apparently not worth the effort as minimal power increase over RB25DE