I believe the "stock" standoffs for a DA are the 2-1/2" ones. That's what they sent me by default. I had to ask for the 1-1/4" standoffs for my Vision... but wish now that I had used the 1-1/4" instead.

No amount of moving things around would get me balanced, even at an inch back from suggested CG and using a Carbon Fiber tailwheel. Had to add 6 ounces of lead to the nose. I also had to cut the back end of the cowl shorter cause it was hitting the gear due to the shorter standoffs. If you use 2-1/2" standoffs you won't have to do that, but I think 3-1/2" (which aren't standard) would be too long. You probably would have problems mounting the cowl at that position.

Tom