I suggest anyone doing an RB25 rebuild take you up on this offer. Not only do they look the same but I've had someone look up the part numbers for R34 RB26 and R34 RB25DET and the numbers are the same.
Also the R33 and R34 RB25DET's both have 9:1 compression ratio which can be a limiting factor in putting lots of boost into them.
Bass Junky has about 250rwkw without lowering the compression ratio but he does have cams as do I.
There doesn't seem to be many people succesfully putting a lot of boost into a NEO without cams or lowering the CR. I can't think of any offhand.
The NEO does have solid lifters as does the RB26 but they are not the same.
The NEO exhaust valves are 1mm bigger than the RB26 items. This could help get more power from the same or less boost all other things equal.
It seems to me that without lowering the CR the NEO can take about as much boost as a non NEO. Depends how far you want to push it, how good/consistant your fuel is, and how well tuned it is. The power levels are probably similar, perhaps a slight advantage to the NEO. If injectors aren't being changed the NEO ones are 350cc but earlier ones are 370cc. which could be a limiting factor.