Ultimately, it's your machine, but I think any color that seems period will look good, if applied well. My Delta 7" pedestal grinder is the original blue-gray Delta used on metal working machines during WW2, both because that fact is a neat piece of history, and because of the sentimental value of the grinder ( my wife found it for me at an industrial surplus house for 90.00, and was grinning ear to ear at her luck). a satin black would look "right", if you polish the hardware and do a neat job; remember, a lot of machine colors back then were kind of muddy to our modern eye, so anything that is a bit subdued will make visual sense. Just don't paint it a neon color, and you can't go far wrong.
Excellent find, by the way.
-James Huston