I would agree with parting tool / calipers / roughing tool followed by
skew, but will add a couple of other thoughts too.

First, when duplicating by hand, it helps to do the same thing, in the
same order, to each item. So it pays to make a story stick to help you
get the same positions along the length of the turning. Then, to make it
easier to set calipers, I have turned a spindle with steps of various
diameters. Not only is it faster to set calipers this way, rather than
using a ruler, it is also more consistent.

The other suggestion may or may not help. I have used it to make morse
taper plugs, but I am not sure if it will scale up well to the job you
have. But what I did was take a piece of plywood and mark out the taper
you want. Then glue some pieces of wood either side of the taper (in
your case something about 6/4 x 6/4 would be ideal) so that you make a
'box' that will fit the taper. Then, when you get the tapers nearly
done, you can stop the lathe and offer the box up to the taper to see if
it fits and check the slope.

It is good that you cut the blanks over long. If you start out with the
finished shape closer to the narrow end of the wood, you give yourself
some slack to play with if things don't go well.

--
Derek Andrews, woodturner

http://www.seafoamwoodturning.com
http://chipshop.blogspot.com
http://groups.yahoo.com/group/toolrest/