Hi and welcome to the forum...
I'n not really clear on what your doing but from what I've gathered it seems that maybe your biggest concern is losing some threads off the end of your stripper bolt? Would you be able to drill... tap... counterbore for snug fit to shoulder diameter. Then use the shoulder that is in the c'bore to prevent the bolt backing out so you won't lose any of your threads? You could put a slight v groove in the shoulder bolt at the location of your set screw. Or just throw a little loctite on it?
It's nice to put any shear or radial load on the shoulder instead of the relief cut at the start of the threads.
But like I said... I'm not real sure what you're after.