Personally, I don't like less than 10 feet for a ridgeline. I don't know if what you have should be sufficient. Probably. I know people do a lot less. But it depends on your entire system, and how/where you pitch.
I have juuust
enough uncut material left over to make two foot beaks instead. I think I'll go back to my original 12' ridgeline idea (or very slightly less - I'll have to cut off an inch or so with tape on it to remove the smaller beak). My other project will just have to wait. If anyone's curious, I wanted to try my hand at homemaking an inflatable mattress. At least I'll have enough scraps to test out some ideas.