1.85:1 is a non-video tape resolution, which is fine if you want it to have the this look on a file that is played back on a computer.
Two ways of doing it – Letterboxing it in FCP and a Widescreen mask 1.85:1 to the 16:9 timeline. This will give you black bars on top and bottom and this is what you would want if you are going to tape.
Crop top and bottom of image. In compressor take a QT of the final movie. (this does not work for AVI so you will need to do another codec and then get that to AVI
New QT Movie
Encoder Tab
Encoder Type: AVI (set options to your needs)
Geometry Tab
Source Inset (Cropping)
Crop to Custom Top 22 | Bottom 22 (this should keep your interlaced field order correct)
Dimensions (encoded pixels: will change to 1920 | 1036 (grayed out)
As you can see their is not that much of a difference between 16:9 (1.78:1) and 1.85:1.