The way I did mine was got to the hardware store and get a grade 8 3/8" fine thread bolt about 6" long. Cut the threaded end off but leave about 3/8" of thread. Then cut the other end off to the desired length that you need.
Then take the rifle bolt apart and cut the bolt handle off flush with the bolt body, then drill a 5/16'' hole in the bolt body where the bolt handle was. Then tap the hole with a 3/8" fine thread tap.
Then cut the ball off of the bolt handle and drill a 3/8" hole where the extension was located, insert the special bolt with the threaded end opisite of the ball. Mig weld the ball to the bolt. CHuck it up in a drill press and dress up weld. Thread new handle into bolt body and heat and bend to the correct angle. Remove and polish new bolt handle. I never welded mine to the bolt body I just used red lock tite.
I will look for some pictures and try to post them.
DRJ