Hi Gary,
That's the way that I make my crank shafts although they are much smaller than yours, as an experiment a made a crank for a single cylinder 10V, Loctite the webs to the 9/32" dia shaft, left overnight to cure and then tried to break the glued webs to no avail, I actually twisted the shaft but still the joints held, I still taper pin crank shafts as well as 603.
I checked the central hole in my rotary table and it's a parallel 3/4" hole, with your comments on how you held the job made me think on how to do similar, in my experiments with high speed flash steam engines with bench revs of 15,000 r.p.m.I made a taper sleeve on the flywheel and pulled the flywheel onto the taper and it never moved, even with a cord start.
when I finish my current project I will make a jig very similar to your idea with a taper. sleeve and a central bolt up thro" the jig with various sleeves to hold various diameters. a bit like the central bolt on the head set of a bicycle,
Thanks for the reply
George.