In my AAC fifth edition reloading guide it says that in a Redhawk with a 7.5" bbl., they got the following using AA#5
215 lead bullet-11.7 starting load- cci 300 primer- win cases- gave 1157 fps
215 lead bullet-13.0 maximum load- cci 300 primer- win cases- gave 1300 fps
I would say based on their own data, that you may want to back down just a bit. Their gun had a longer barrel than yours, so that may account for some of the velocity difference even though your load is a bit warmer. There is no reason to push an old classic like yours too hard.
I hope that helps.