OS 3.9 needs a 68020, a lot of RAM, a screen mode with 1:1 aspect and a lot of colors.
With OCS chipset 16 colors is the maximum and the absolute minimum for OS 3.9 to look ok.
640x512x16 needs 160 kb of chip RAM. Another 160 KB for the background image. And a bit more for the icons.
If you can afford all this, then it's ok. You'll probably not be able to run any game with this setup.
