Can't think of anything that's compatible--needles, shuttle, bobbin are all different. Singer long bobbins will work in your Davis but must be wound on a Singer. This thread might be of help:
http://www.quiltingboard.com/vintage...e-t263658.html
Your Davis is a "Vertical Feed" and the Davis Unique is an Underfeed but they share the same needle, bobbin, and shuttle.
If you joint the Davis VF Yahoo group they have an owners manual in "Files" for your Davis
https://groups.yahoo.com/neo/groups/davis_vf/info
Jon