Does a 3.25" hole allow the duct on to the back of they eyeball dash vent. I cant remember the size of duct work needed. Have you drawn the extension tube off the back of the forward triangle? I think I made my hole slightly larger in that area, and may have even had it turn the corner of the flange slightly so that I was not trying to bend ductwork at an angle coming of the back of the stub tube on the back of the triangle piece?
It was so long ago that I looked at that part I can't even remember what photo I copied.
I can't even remember of the top of my head what size I made that hole.
I think I would have made it match the holes on the spare tire well cut out, just for consistency. My assumption at the time is that they would have used a punch tool that they had on hand, so just used a size that I knew they had.