Any comparison is useless unless you have quantative data on invivo conversion rates and at what dose (if any) enzymatic limitation on conversion occurs. I don't know of any study that has measured these factors. Where did you get your bioavailability numbers?
When I asked Pat Arnold about enzymatic limitation of 3HSD he said "we don't know." He thinks it is really high though because the limitation for 17-HSD is extremely high evidenced by the fact that supplementation with very large amounts of andro results in very high levels of testosterone.
This would indicate that Deca-like levels of nandrolone would be possible if you were willing to pop enough Nor-diol. However from what I have read the straight Deca would be the more cost effective (albeit illegal) means of obtaining the desired level of nandrolone in the body.
Of course transdermals are another story and I know very little about those.
In theory, it should work, but there is a limit to how much your body can actually convert, due to lack of enzymes to convert. Hmm i was wondering is there a way to add more of these enzymes that are used to convert?