Now after all this you throw a monkey wrench into the equation. The arrows are 31 1/8" and not 29" as you originally asked. That's lot of difference.
So what is the draw length of the bow? I don't need to know yours. You'll draw back the bow to wherever the cam stops so that doesn't mean anything. What does the draw length of the bow measure?
If you can have somebody merk an arrow about 1" in front of the rest while you are standing at full draw and then measure from the throat of the nock to where ever it's amrked. If the bow's draw length is 29" you may be able to shoo the arrows cut down to 28" or so. This would match the spine much better for the bow.
So maybe get the arrows cut down and new inserts installed. That's something Walmart can't do for you and it may have been included in the price at an archery shop, but it won't be free now. So how much did you really save?