I came across this thread by chance when looking for some thing totally unrelated. Now this would be a fascinating engine build indeed and something in the vein of the prototype development of MGA twin cam engine with the BMC B series block.
Here's a couple of pix and the link to the discussion. It may be a load of BS as it peters out but the concept is interesting.
It's never going to work because you will have one head with the inlet in the valley, and the other head exhausting into the valley because both the heads are the same. It's for the same reason (amongst many others) that you cant put 2 sprint heads on a stag V8 engine.