"That Pentangle version does it no justice, despite McShea's ability: again the lyricism is lost by the rigid timing,"

Exactly my point. It seems to me that you may be seeking a much more *contemporary* dramatic or theatrical style arrangement (which is why I asked you to imagine how Elaine Page would sing WoW*) of a traditional melody - which re-shapes the original tempo and dynamics, to suit a more modern 'soaring' rock-opera-ish vocal styling.





* albeit that not being the original melody!