There is nothing wrong with shooting an "overspined" arrow as long as it's not doing anything funky. Out of everyindoor or 3Dbow setup I've ever shot, I've never seen one that didn't fly well with a severely "overspined" arrow setup. The only time I worry about correct spine is for a field/fita archery setup where I will be shooting out to 90 meters, and a fixed blade broadhead hunting shaft.

Every of my best indoor games, and even my best 3D games were shot with "overspined" arrows. I cut them 1/2" in front of the blade on my rest, and never seem to have a problem.