Ben, I suspect that different sealers on the same raw weight shafts would yield different final arrow weights. I have only used gasket lacqer. I just made a couple of dozen Douglas Fir up and unless I am figuring wrong, I believe that my suggestion on raw shaft weight Douglas Fir to finished arrow weight is correct.
Just for information's sake I have also noticed that gasket lacquer on Douglas Fir adds just about twice as much weight as it does on Cedar due to the physical differences in the wood. Also I use water-based stains except for once when I put on some oil-based and I remember the finished arrows came out a bit heavier.
How are things "down under"? Hope you are doing well.