Firstly I didn’t check my typing in the previous post. I said “a couple hundred points” when I meant a couple hundred grains.
If you move the arrow up the string, you are changing how the bow casts the arrow. You can compensate for incorrect spine by moving the arrow up or down the string. Usually, if you move the arrow farther up the string you compensate for an underspined arrow. But that’s not always the case. I am just guessing, but I think you still need more weight to make that arrow fly right.
But if it was me, I’d get a weaker arrow and start over. By the time you get those 350’s flying right they will be heavier than the bow….
Those 350’s are thicker than 250’s as well. Which pushes them away from the riser and means they need to have a weaker spine to fly right.
But you are there, not me. So take these words as not worth much.