I don't know about the oil-bath for the valve springs. Seems you'd get a LOT of burnt oil from leaking down the valve stem.
I expect the increased rail height on your A3 heads are to accommodate a sturdier roller rocker valve train, not to maintain a larger reservoir of oil in the heads. But then again, I'm just speculating. Hopefully Dan Jones weigh's in on this one.
Check out this thread for pics of oil drain lines in the heads:
http://pantera.infopop.cc/eve/...?r=76310798#76310798
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