I hate to be the guy who throws cold water, but --
It is not unusual for a good 3D shooter or bowhunter to come indoors and shoot pretty good. However, indoor is a mentally grueling game and these guys usually don't last too long with the higher scores. The guys that shoot 55 X and above are shooting hundreds of arrows a week and it is more for mental discipline that for physical. It's hard to avoid some form of target panic when you are shooting that much. Also, most will have a bow that with a draw weight in the 35 to 50 lb range to reduce shoulder and elbow injurys. The mass weight on these bows is about double that of your bow. This is to make it more stable on the target.
There is nothing wrong with your set-up. You can have some success and a lot of fun shooting indoor with it, but it won't take you to the top of the heap indoors. Your shoulders and elbows will give out before you get there.
I hope that I am not discouraging you. Indoor shooting is my passion. I'm not as good as I will be down the road. I'm suffering through an elbow injury that has lasted several months. Like you I started with a hunting rig, but quickly saw the need for a more specialized bow. I will be shooting in my state indoor championship on the first weekend in April. Since I think that I stand a chance to win, it's very appropriate that the first day is April Fools Day