For a loaner bike, I'd keep it cheap. Wald or similar low price steel swept bar. SunRace friction shifters. Pretty much how I had my Univega set up for a couple of years before I got fancy. It worked fine.
Is the correct answer.
Hang onto the Mirage shifters and drop bars in your parts bin or whatever, but definitely for the sake of simplicity, friction shifters are the way to go.