19nordiol and 4ad do use the same conversion enzyme ( 3HSD ) which does make them a poor choice to stack together because the enzyme will only be able to convert a certain amount so alot of the PH will go to waste. 19nordione uses a different enzyme ( 17HSD) than 4ad but he problem with nordione is that it only has about 5- 6 % conversion. I tried a 4ad and 19nordiol stack about a year and a half ago ( it was oral, so the trans. will be better ) I usd 1200mg of 4ad and 1200mg of 19nordiol, I did not see much in terms of gains, I got alot of water retention, I saw about what one would get by just takin 4ad or 19nor in these doses by themselves. You could try a 19nordione and 4ad stack but you would have to use abour 3 times the amount of 19nordiol you would use because of the poor conversion.
It dosnt sound like 19nor and 4ad will be a good stack, but I would be interseted to see how this stack ends up rating transdermally snce Idid it orally.