Warren in Lancaster, PA
I have been using chisels that are about 200 years old. Usually the bolsters are somewhat larger than what you are making, and the octagonal handle tapers to within 1/32 or so of the bolster dimension. Occasionally it appears that they filed the bolster flush after the handle is on. On narrower chisels the bolster is smaller, the handles are somewhat smaller and the taper is more pronounced.

In the 17th century the taper in width is quite pronounced, but during the 18th century the taper gradually diminished and by the mid 19th century had disappeared. I like a little bit of taper.

The taper in thickness is pretty extreme; the thickness just before the bolster can be four times the thickness at the bevel. These chisels generally don't have side bevels.

I am used to tangs that diminish to a sharper point than what you show.

I have watched a blacksmith make a bolster. They take a little worm of iron and bend it around the shank and then forge weld it to the chisel. Then they work it with the hammer and finally refine with a file.