Not that I care, but when modifying a car it has to all meet the ADR standards.
No changing can allowed, no more than a 20% more power etc.
There's something about changing to an older engine somewhere, which is a no no, but given an rb30 comes out with one cam, using a different head and cams although stock, is still changing the cam.
That's easily sorted by an emissions test though.
The 30 bottom end and 26 or 25 head is a bit of an oddball as far as the standards and law goes.