Hey Bill,
Somewhere, (from another post), it was suggested that 1/2" x 3/8", or 5/8" x 1/2" copper to copper sweat bushings worked for this application pretty good.
They are made of bronze roundstock, not copper, like the fitting reducers.
As I had mine made up at my shop I'm not looking to get anymore.
They are available at some of the more well stocked plumbing supply stores.
Might be something to see the next time your in Home Cheapo.
Al