1.37 " 24 TPI I believe.......which is the same as a freewheel or track cog diameter, also same as ball type bottom bracket lockring, which makes a good substitute for a real lockring
ya, locktite will work, please put a brake on it though.......if a regular track hub can strip the lockring right off, a lockring threaded the same way isnt gonna stop it from coming off either, but most reg freewheel threaded hubs have a little more meat to thread onto.
Ive done something similar and rode it for a year w/o any problems, use the blue loctite, just be advised, once its on, getting it back off isnt so easy, soaking in finger nail polish remover will soften the loctite, sort of. Blue loctite is some serious stuff, you can glue pieces of metal together and its almost permanent. Ive used it on all sorts of things. Once I used it to glue a water neck housing in a ford back together that I snapped in half, thing held together even under all that heat.