If I were doing this job, I would use a valve with female threads and 2
male adapters. I'd sweat one m/a to one of the pipes, install the valve,
sweat a piece of pipe about a foot or so, if space permits, to the other
m/a, then screw it to the valve, and lastly hook that piece of copper to
the rest of the system. That way there is no chance of messing up the
valve. Of course the main reason I would do it that way is that I only
use silver solder. Besides not liking / trusting soft solder, after more
years than I'd like to admit in the a/c /ref trade using silver solder
and almost no experience with soft solder, I always have the stuff handy
to SS. But regardless of which solder it usually seems easier to me to
sweat copper-copper than copper-brass. YMMV Good luck Larry