I have a tapering jig that I use to taper the last 10" of my shafts which I made from a 34" piece of 2" x 2" hard rock maple with a 1/4" deep "V" groove cut full length. I set a finishing nail just below flush near one end.
As you state - straighten the shaft, taper for nock, straighten again. I usually straighten the shafts at least twice a day apart before I grind the nock and head tapers.
I use a Bowyer's Edge scraping plane (from Dean Torges - now likely unavailable) and start with marks every 2" up the shaft (2", 4", 6", 8" & 10"). With a pencil I draw a line at these distances around the shaft (twisting it by hand in the groove.
Starting at the 2" mark I scrape towards the nock end and move all around the shaft (usually 20 or 21 scrapes). Then I move up to the 4" and repeat - taking it all the way to the nock each scrape.
By the time it has been done from all four distances it is a shaft tapered the last 10". I round it up with 200 grit sandpaper (on a block) and then smooth it up with #000 3M buffing pad to smooth it all up.
There is your nice 11/32" shaft tapered down for a 5/16" nock.