I could not imagine having a ridge line that long. I find more than enough coverage with the standard length and coverage for me with a longer ridge line would be less.
With a longer ridgeline on a warbonnet blackbird it would be difficult to get a low pitch on your tarp. As most are aware a warbonnet blackbird is set with its strapping apx 30 degrees.
Try getting a low pitch with a longer ridge line. You will find it a bit difficult to do on a blackbird.