Great post!
I do almost the exactly same thing with my arrows, but I don't seal them (for no particular good reason).
One thing that I do that is a bit different is that I actually weigh all the shafts, select those that are in the ballpark for grains/inch (for my final shaft length), straighten them, rough spine them, cut them to the length that I want, then weigh each shaft (and mark with a piece of tape)-----then create my point on the duplex nails, then figure out how much to cut off each nail so that the total shaft + shortened nail = my desired arrow weight.
It's pretty easy to allocate a certain number of grains per 1/4" of nail (depending on your nails), and then you can just cut off 1/2", 1/4", etc...or more to create arrows that are more or less weight matched.
Cheers,
J