NPP has more nandrolone but because deca is longer acting you'll end up with more nandrolone present in your blood by the 2nd week and throughout your cycle. So if you use say, 400mg/wk of deca you should use 400mg/wk the first 2 and then go up to get the dose you're use to. I go up 100mg/per 400mg deca so I would go 400 then 500.
Someone can spread sheet it and give you more exact numbers but that works for me.