yes, a ball valve with a 3/4" NPT to GHT adapter is the ideal solution - as it'll last longer than the washer in a boiler drain as well.
However, if you use one, I would get a brass GHT cap for the outlet, preferably on a chain if you can find one, to cap off the opening when not in use. All it takes is a misplaced elbow to take a quarter turn ball valve from shut to WFO.
nate