Rover v8 heads oilways

[bigdoctvr]

The tvr350i (oil pressure ok,pump gears replaced & HD pressure spring fitted) has always seemed a bit sparse on oil at the topend, I can run the engine without covers and only get a dribble from the rocker sides(I've checked the feed hole alignment in the rocker shaft) on the last strip I did notice that the rear oilways in both heads had not been drilled, leaving only the front feed to the rocker, I assumed this was to increase oil pressure at the bottom end? while its not gone bang (yet) the top does seen to be hot poss loss of the coolant function of the oil, is this a known mod? anyone else come across this...
cheers Dave