Is it a series 1 or 2.
If its a series 1 grab an R33 RB26 crank, possibly rb26 rods and pistons.
If thats not an option then be sure you throw an oil pump drive collar on the stock crank as to prevent future oil pump breakage.
If you can't find an R33 RB26 crank be sure to throw the crank collar on an R32 rb26 crank.
At least with a set of stock rb26 rods you can feel safe pushing up to 400rwkw.
The RB26 crank gives you a little more displacement, throw that together with 87mm pistons and you have 2628cc vs the rb25's standard of 2498cc.
There's one bloke that recently used an RB26 block, std rb30 crank that has been destroked, rb26 rods and custom pistons for 2.9ltrs all within the std rb26 block. Allthough the r/s ratio isn't ideal it is holding together at around 400rwkw if I remember correctly.
So thats another option to discuss with your engine builder, see what he thinks.