So first I marked the position of the bridge with a piece of electrical tape on the body forward of the bridge, and I lowered the tension on the strings so that I could flip the bridge forward onto the tape and remove it without scratching the finish. Then I scribed along the bottom of each foot on the bridge a mark of how much material I wanted to remove. slowly with some sand paper on the edge of a table I sanded until I met the mark and matched the radius of the face. But I had to keep working it until I couldn't see any gap on either side. I didn't want the bridge to put uneven pressure on the face of the mandolin. That process took over 2 hours.
Then I used the turn wheels to raise the top part of the bridge until there wasn't any fret buzz. I was getting just a little on the D string. I had to bring the strings up to pitch and back down again a couple of times and turn the wheels. I coudln't turn the wheels with the strings under tension. I finally got the height to what I read online was ok. .070 inch on the G string above the fret at the octave and .060 on the E string.
Now this cheap import is about as good as it's going to get. There's no fret buzz and it really did improve the intonation. Over the weekend I replaced the strings with D'Addario J73 Phosphor Bronze Light ones. That seemed to help the intonation a little too because I could hear the harmonic overtones better and that helped tuning.
(photo will get bigger if you click on it)