Ok well here's what i was getting at; im building another motor now for my GTR (no, nothings wrong with the current one), and im doing a spare head for it aswel just for the sake of trying something no one has done with an RB head before. (dont ask specs or details, will release when ready)
Now, its twin low mounts, target power at crank is 750hp same as your target Noel but also like you the fattest low end and midrange possible with an RB based block BUT still retaining the RB "revvyness". The first head is what one place call ultimate and the second is a totally different direction.
End of the day someone might come along and think its no good being on twins for example - cant please everybody so may aswel make what you think the ultimate is and be happy with that IMO