Going by your specs, the 3-49's are right on the edge of their spine range. You wouldn't have any problems bumping up to 3-60. Might even be better off to do so, especially for broadheads. For me, broadheads tune a bit easier on stiffer shafts.

Don't use 5" feathers on ACC's. You're begging for clearance problems if you do and, after shooting ACC's off my recurve and longbow, I've found you just don't need that much feather for a small diameter arrow. 4" feathers will stabilize a broadhead just fine on ACC's.

In fact, since feathers generally have the stabilizing power of vanes that are an inch longer, you might try fletching some up with 3" feathers and giving them a try. Compare how they shoot your 100 gn broadheads to some arrows fletched with 4" vanes.