I wonder if your arrow isn't too weak spined with all that weight up front and shooting a full length shaft? However, you said you had bareshafted it and "thought we had dialed it in". Did you actually get good arrow flight when you shot bare shafts, or did you mean something else? How far out did you shoot the bare shafts?
For a fairly small investment of $8 each, you can get Gold Tip tuning shafts in 5575 and 7595 sizes from Black Widow, and possibly other places. They come with all the weights and inserts you need. With Gold Tip, you can put weights on the back as well as the front, so you can end up with the weight you want and maybe get a better balanced arrow. My guess, at 30" + length, you will want the 7595, but the tuning shafts are cheap enough that you could try both. The advantage of being able to put weights in the back is that you can get the overall weight you want without overly weakening the spine. Possibly you could achieve the same result by using weight tubes in your arrows rather than putting all the weight up front.
I don't know how comfortable you are shooting a 71# bow; it would be more than I could handle. A 30" draw is getting close to the maximum for a 60" bow, so you would get a certain amount of finger pinch. Shooting split fingers, you may be pressing down on the arrow nock at full draw, which causes the arrow to rebound. All of these factors may or may not contribute to erratic arrow flight, depending on whether they are problems for you.