If you want to use it for drifting in stock forms the rb25 and rb26 the 25 will be more reliable as the 25 arent effected as badly by oil starvation and while drifting the oil is going to be thrown around everywhere. I would rather a single turbo like a 3071 or 3076 with 300kw on a safe tune which is perfect for a r33 drift car similar to my setup than going a twin with the 26.
In regards to wanting to put a 26 head on the 25 bottom I dont really see any worthwhile gains youll have for one youll lose vct. Imo stick with the 25 slap on the usual bolt ons, chuck in some 256 poncams if you want to beef up the midrange a bit and tune on e85 for a safe 300kw all day everyday cheapest and most effective way for a r33 drift car.