So, as a related question to what has been discussed....
The RB head has the proper cylinder spacing and head bolt pattern to work, it's just the oiling and cooling that has to be modified?
If it's really that straight forward as far as bolting on to the block, I'm in. Cam gears can be made or modfied FAR easier than casting a completly new head design, re-routing oiling and cooling is not usually that difficult, though cooling path changing is generally not for the feint of heart to attempt.
Is there anything that documents and attempts at putting an RB head on an L-series?
I just want to counter one point:
I don't see that as being completly accurate, yes the L-series blocks have been around that long, but the technology that we are wanting to use or adapt in the stock forms they are have been around far shorter periods of time than that. We may just simply not be looking at the right offerings out there, and there may still be a head that will fit, with less modification. I've seen new adaptations to older products, just simply because no one had looked at combining those items until now, or a long period of time later, when you would have thought that it would have already been tried before.
I'm still looking to swap a different engine, because it will layout better in the engine bay with my plans, but like I said before if a high flowing head can be found that will mate to the L-series block, I'd seriously consider keeping the L-series bottom end.